bindings: Do not access @@iterator twice when converting union to sequence

A rough approximation of https://heycam.github.io/webidl/#es-union when
trying to convert an ES value to an IDL sequence or frozen array is:
1. Call the GetMethod abstract ES operation to retrieve the @@iterator
   property.
2. If it is not undefined, invoke
   https://heycam.github.io/webidl/#create-sequence-from-iterable with the
   ES value and the method obtained above.

So far, we were implementing it roughly like this:
1. Call the GetMethod abstract ES operation to retrieve the @@iterator
   property.
2. Invoke https://heycam.github.io/webidl/#es-sequence with the ES value,
   which disregards the method obtained in step 1 and goes through the whole
   process of calling GetMethod again and using that to create a sequence
   from an interable.

This is obviously not compliant with the spec, and the multiple calls to the
GetMethod abstract operation are user-visible, as can be seen in the test
case attached to the bug 1024388.

Properly fixing this requires changes to a few different classes and
functions:
* Make HasCallableIteratorSymbol(), which is called by the overload
  resolution algorithm implementation, be a small wrapper around
  GetEsIteratorMethod(). While HasCallableIteratorSymbol() precedes
  GetEsIteratorMethod(), the latter's implementation is more spec-compliant.
* Add a move constructor to ScriptIterator, as well as a static method that
  can create a ScriptIterator out of an ES value by invoking
  GetEsIteratorMethod() and GetEsIteratorWithMethod() underneath.
* Make NativeValueTraits<IDLSequence<T>>::ConvertSequenceSlow() take a
  ScriptIterator rather than a v8::Local<v8::Object>, which allows us to
  delegate getting an iterator out of an iterable object to the static
  ScriptIterator method mentioned above. This also helps reduce the size of
  the generated per-type NativeValueTraits<IDLSequence<T>> template code.
* Analogously, invoke ScriptIterator::FromIterable() in the union conversion
  code, and invoke a new NativeValueTraits<IDLSequence<T>>::NativeValue()
  overload that takes a ScriptIterator, so that we do not access the
  @@iterator property multiple times in the union conversion code.

Bug: 1024388
Change-Id: I47e6c0ca881e6e77f883ee78b5e1611138cdcc4a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1917169
Commit-Queue: Raphael Kubo da Costa <raphael.kubo.da.costa@intel.com>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#716960}

third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h

@@ -416,6 +416,7 @@ struct NativeValueTraits<IDLSequence<T>>
   static ImplType NativeValue(v8::Isolate* isolate,
                               v8::Local<v8::Value> value,
                               ExceptionState& exception_state) {
+    // 1. If Type(V) is not Object, throw a TypeError.
     if (!value->IsObject()) {
       exception_state.ThrowTypeError(
           "The provided value cannot be converted to a sequence.");
@@ -431,7 +432,21 @@ struct NativeValueTraits<IDLSequence<T>>
       ConvertSequenceFast(isolate, value.As<v8::Array>(), exception_state,
                           result);
     } else {
-      ConvertSequenceSlow(isolate, value.As<v8::Object>(), exception_state,
+      // 2. Let method be ? GetMethod(V, @@iterator).
+      // 3. If method is undefined, throw a TypeError.
+      // 4. Return the result of creating a sequence from V and method.
+      auto script_iterator = ScriptIterator::FromIterable(
+          isolate, value.As<v8::Object>(), exception_state);
+      if (exception_state.HadException())
+        return ImplType();
+      if (script_iterator.IsNull()) {
+        // A null ScriptIterator with an empty |exception_state| means the
+        // object is lacking a callable @@iterator property.
+        exception_state.ThrowTypeError(
+            "The object must have a callable @@iterator property.");
+        return ImplType();
+      }
+      ConvertSequenceSlow(isolate, std::move(script_iterator), exception_state,
                           result);
     }
 
@@ -440,6 +455,19 @@ struct NativeValueTraits<IDLSequence<T>>
     return result;
   }
 
+  // https://heycam.github.io/webidl/#es-sequence
+  // This is a special case, used when converting an IDL union that contains a
+  // sequence or frozen array type.
+  static ImplType NativeValue(v8::Isolate* isolate,
+                              ScriptIterator script_iterator,
+                              ExceptionState& exception_state) {
+    DCHECK(!script_iterator.IsNull());
+    ImplType result;
+    ConvertSequenceSlow(isolate, std::move(script_iterator), exception_state,
+                        result);
+    return result;
+  }
+
  private:
   // Fast case: we're interating over an Array that adheres to
   // %ArrayIteratorPrototype%'s protocol.
@@ -470,38 +498,15 @@ struct NativeValueTraits<IDLSequence<T>>
 
   // Slow case: follow WebIDL's "Creating a sequence from an iterable" steps to
   // iterate through each element.
-  // https://heycam.github.io/webidl/#create-sequence-from-iterable
   static void ConvertSequenceSlow(v8::Isolate* isolate,
-                                  v8::Local<v8::Object> v8_object,
+                                  ScriptIterator script_iterator,
                                   ExceptionState& exception_state,
                                   ImplType& result) {
-    // https://heycam.github.io/webidl/#es-sequence
-    // 2. Let method be ? GetMethod(V, @@iterator).
-    // 3. If method is undefined, throw a TypeError.
-    // 4. Return the result of creating a sequence from V and method.
-    const v8::Local<v8::Function> iterator_method =
-        GetEsIteratorMethod(isolate, v8_object, exception_state);
-    if (exception_state.HadException())
-      return;
-    if (iterator_method.IsEmpty()) {
-      exception_state.ThrowTypeError("Iterator getter is not callable.");
-      return;
-    }
-
     // https://heycam.github.io/webidl/#create-sequence-from-iterable
-    // To create an IDL value of type sequence<T> given an iterable iterable
-    // and an iterator getter method, perform the following steps:
-    // 1. Let iter be ? GetIterator(iterable, sync, method).
-    const v8::Local<v8::Object> iterator = GetEsIteratorWithMethod(
-        isolate, iterator_method, v8_object, exception_state);
-    if (exception_state.HadException())
-      return;
-
     // 2. Initialize i to be 0.
     // 3. Repeat:
     ExecutionContext* execution_context =
         ToExecutionContext(isolate->GetCurrentContext());
-    ScriptIterator script_iterator(iterator, isolate);
     while (script_iterator.Next(execution_context, exception_state)) {
       // 3.1. Let next be ? IteratorStep(iter).
       // 3.2. If next is false, then return an IDL sequence value of type

third_party/blink/renderer/bindings/core/v8/script_iterator.cc

@@ -11,6 +11,28 @@
 
 namespace blink {
 
+// static
+ScriptIterator ScriptIterator::FromIterable(v8::Isolate* isolate,
+                                            v8::Local<v8::Object> value,
+                                            ExceptionState& exception_state) {
+  // First, call the GetMethod(V, @@iterator) abstract ES operation.
+  const v8::Local<v8::Function> iterator_method =
+      GetEsIteratorMethod(isolate, value, exception_state);
+  if (exception_state.HadException())
+    return ScriptIterator(nullptr);
+  if (iterator_method.IsEmpty())
+    return ScriptIterator(nullptr);
+
+  // Use the method returned above to invoke the GetIterator(V, sync, method)
+  // abstract ES operation.
+  const v8::Local<v8::Object> iterator =
+      GetEsIteratorWithMethod(isolate, iterator_method, value, exception_state);
+  if (exception_state.HadException())
+    return ScriptIterator(nullptr);
+
+  return ScriptIterator(iterator, isolate);
+}
+
 ScriptIterator::ScriptIterator(v8::Local<v8::Object> iterator,
                                v8::Isolate* isolate)
     : isolate_(isolate),

third_party/blink/renderer/bindings/core/v8/script_iterator.h

@@ -14,14 +14,67 @@ namespace blink {
 class ExceptionState;
 class ExecutionContext;
 
+// This class provides a wrapper for iterating over any ES object that
+// implements the iterable and iterator protocols. Namely:
+// * The object or an object in its prototype chain has an @@iterator property
+//   that is a function that returns an iterator object.
+// * The iterator object has a next() method that returns an object with at
+//   least two properties:
+//   1. done: A boolean indicating whether iteration should stop. Can be
+//      omitted when false.
+//   2. value: Any object. Can be omitted when |done| is true.
+//
+// In general, this class should be preferred over using the
+// GetEsIteratorMethod() and GetEsIteratorWithMethod() functions directly.
+//
+// Usage:
+//   v8::Local<v8::Object> es_object = ...;
+//   auto script_iterator = ScriptIterator::FromIterable(
+//       isolate, es_object, exception_state,
+//       ScriptIterator::ConversionFailureMode::kDoNotThrowTypeError);
+//   if (exception_state.HadException())
+//     return;
+//   if (!script_iterator.IsNull()) {
+//     while (script_iterator.Next(execution_context, exception_state)) {
+//       // V8 may have thrown an exception.
+//       if (exception_state.HadException())
+//         return;
+//       v8::Local<v8::Value> value =
+//           script_iterator.GetValue().ToLocalChecked();
+//       // Do something with |value|.
+//     }
+//   }
+//   // If the very first call to Next() throws, the loop above will not be
+//   // entered, so we need to catch any exceptions here.
+//   if (exception_state.HadException())
+//     return;
 class CORE_EXPORT ScriptIterator {
   STACK_ALLOCATED();
 
  public:
+  // Creates a ScriptIterator out of an ES object that implements the iterable
+  // and iterator protocols.
+  // Both the return value and the ExceptionState should be checked:
+  // - The ExceptionState will contain an exception if V8 throws one, or if the
+  //   ES objects do not conform to the expected protocols. In this case, the
+  //   returned ScriptIterator will be null.
+  // - ScriptIterator can be null even if there is no exception. In this case,
+  //   it indicates that the given ES object does not have an @@iterator
+  //   property.
+  static ScriptIterator FromIterable(v8::Isolate*,
+                                     v8::Local<v8::Object>,
+                                     ExceptionState&);
+
   ScriptIterator(std::nullptr_t) : isolate_(nullptr), done_(true) {}
 
   ScriptIterator(v8::Local<v8::Object> iterator, v8::Isolate*);
 
+  ScriptIterator(ScriptIterator&&) noexcept = default;
+  ScriptIterator& operator=(ScriptIterator&&) noexcept = default;
+
+  ScriptIterator(const ScriptIterator&) = delete;
+  ScriptIterator& operator=(const ScriptIterator&) = delete;
+
   bool IsNull() const { return iterator_.IsEmpty(); }
 
   // Returns true if the iterator is still not done.

third_party/blink/renderer/bindings/core/v8/v8_binding_for_core.cc

@@ -872,16 +872,9 @@ bool HasCallableIteratorSymbol(v8::Isolate* isolate,
                                ExceptionState& exception_state) {
   if (!value->IsObject())
     return false;
-  v8::TryCatch block(isolate);
-  v8::Local<v8::Context> context = isolate->GetCurrentContext();
-  v8::Local<v8::Value> iterator_getter;
-  if (!value.As<v8::Object>()
-           ->Get(context, v8::Symbol::GetIterator(isolate))
-           .ToLocal(&iterator_getter)) {
-    exception_state.RethrowV8Exception(block.Exception());
-    return false;
-  }
-  return iterator_getter->IsFunction();
+  v8::Local<v8::Function> iterator_method =
+      GetEsIteratorMethod(isolate, value.As<v8::Object>(), exception_state);
+  return !iterator_method.IsEmpty();
 }
 
 v8::Isolate* ToIsolate(const LocalFrame* frame) {

third_party/blink/renderer/bindings/scripts/v8_union.py

@@ -133,6 +133,7 @@ def _update_includes_and_forward_decls(member, info_provider):
             _update_includes_and_forward_decls(member.value_type, info_provider)
         elif member.is_array_or_sequence_type:
             _update_includes_and_forward_decls(member.element_type, info_provider)
+            cpp_includes.add('bindings/core/v8/script_iterator.h')
         elif member.is_union_type:
             # Reaching this block means we have a union that is inside a
             # record or sequence.
@@ -146,6 +147,14 @@ def member_context(member, info_provider):
     if member.is_nullable:
         member = member.inner_type
     type_name = (member.inner_type if member.is_annotated_type else member).name
+    # When converting a sequence or frozen array, we need to call the GetMethod(V, @@iterator)
+    # ES abstract operation and then use the result of that call to create a sequence from an
+    # iterable. For the purposes of this method, it means we need to pass |script_iterator|
+    # rather than |v8_value| in v8_value_to_local_cpp_value().
+    if member.is_array_or_sequence_type:
+        v8_value_name = 'std::move(script_iterator)'
+    else:
+        v8_value_name = 'v8_value'
     return {
         'cpp_name': to_snake_case(v8_utilities.cpp_name(member)),
         'cpp_type': member.cpp_type_args(used_in_cpp_sequence=True),
@@ -162,6 +171,6 @@ def member_context(member, info_provider):
         'specific_type_enum': 'k' + member.name,
         'type_name': type_name,
         'v8_value_to_local_cpp_value': member.v8_value_to_local_cpp_value(
-            {}, 'v8_value', 'cpp_value', isolate='isolate',
+            {}, v8_value_name, 'cpp_value', isolate='isolate',
             use_exception_state=True)
     }

third_party/blink/renderer/bindings/templates/union_container.cc.tmpl

@@ -114,15 +114,22 @@ void {{v8_class}}::ToImpl(
   {% endif %}
   {% if array_or_sequence_type %}
   {# 11.1, 11.2. Sequences and frozen arrays #}
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    {{v8_value_to_local_cpp_value(array_or_sequence_type) | trim | indent}}
-    {% if array_or_sequence_type.enum_values %}
-    {{declare_enum_validation_variable(array_or_sequence_type.enum_values) | trim | indent(4)}}
-    if (!IsValidEnum(cpp_value, kValidValues, base::size(kValidValues), "{{array_or_sequence_type.enum_type}}", exception_state))
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
+    if (exception_state.HadException())
       return;
-    {% endif %}
-    impl.Set{{array_or_sequence_type.type_name}}(cpp_value);
-    return;
+    if (!script_iterator.IsNull()) {
+      {{v8_value_to_local_cpp_value(array_or_sequence_type) | trim | indent(6)}}
+      {% if array_or_sequence_type.enum_values %}
+      {{declare_enum_validation_variable(array_or_sequence_type.enum_values) | trim | indent(6)}}
+      if (!IsValidEnum(cpp_value, kValidValues, base::size(kValidValues),
+                       "{{array_or_sequence_type.enum_type}}", exception_state))
+        return;
+      {% endif %}
+      impl.Set{{array_or_sequence_type.type_name}}(cpp_value);
+      return;
+    }
   }
 
   {% endif %}
@@ -232,3 +239,4 @@ v8::Local<v8::Value> ToV8(const {{cpp_class}}& impl, v8::Local<v8::Object> creat
 }  // namespace blink
 
 {% endfilter %}{# format_blink_cpp_source_code #}
+

third_party/blink/renderer/bindings/tests/results/core/array_buffer_or_array_buffer_view_or_dictionary.cc

@@ -140,3 +140,4 @@ ArrayBufferOrArrayBufferViewOrDictionary NativeValueTraits<ArrayBufferOrArrayBuf
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/boolean_or_element_sequence.cc

@@ -13,6 +13,7 @@
 #include "base/stl_util.h"
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_element.h"
 #include "third_party/blink/renderer/core/css/cssom/element_computed_style_map.h"
@@ -79,12 +80,18 @@ void V8BooleanOrElementSequence::ToImpl(
   if (conversion_mode == UnionTypeConversionMode::kNullable && IsUndefinedOrNull(v8_value))
     return;
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    HeapVector<Member<Element>> cpp_value = NativeValueTraits<IDLSequence<Element>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    impl.SetElementSequence(cpp_value);
-    return;
+    if (!script_iterator.IsNull()) {
+      HeapVector<Member<Element>> cpp_value = NativeValueTraits<IDLSequence<Element>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      impl.SetElementSequence(cpp_value);
+      return;
+    }
   }
 
   if (v8_value->IsBoolean()) {
@@ -120,3 +127,4 @@ BooleanOrElementSequence NativeValueTraits<BooleanOrElementSequence>::NativeValu
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/boolean_or_string_or_unrestricted_double.cc

@@ -135,3 +135,4 @@ BooleanOrStringOrUnrestrictedDouble NativeValueTraits<BooleanOrStringOrUnrestric
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/boolean_or_test_callback_interface.cc

@@ -113,3 +113,4 @@ BooleanOrTestCallbackInterface NativeValueTraits<BooleanOrTestCallbackInterface>
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/byte_string_or_node_list.cc

@@ -115,3 +115,4 @@ ByteStringOrNodeList NativeValueTraits<ByteStringOrNodeList>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/byte_string_sequence_sequence_or_byte_string_byte_string_record.cc

@@ -13,6 +13,7 @@
 #include "base/stl_util.h"
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 
 namespace blink {
@@ -72,12 +73,18 @@ void V8ByteStringSequenceSequenceOrByteStringByteStringRecord::ToImpl(
   if (conversion_mode == UnionTypeConversionMode::kNullable && IsUndefinedOrNull(v8_value))
     return;
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    Vector<Vector<String>> cpp_value = NativeValueTraits<IDLSequence<IDLSequence<IDLByteString>>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    impl.SetByteStringSequenceSequence(cpp_value);
-    return;
+    if (!script_iterator.IsNull()) {
+      Vector<Vector<String>> cpp_value = NativeValueTraits<IDLSequence<IDLSequence<IDLByteString>>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      impl.SetByteStringSequenceSequence(cpp_value);
+      return;
+    }
   }
 
   if (v8_value->IsObject()) {
@@ -113,3 +120,4 @@ ByteStringSequenceSequenceOrByteStringByteStringRecord NativeValueTraits<ByteStr
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/double_or_double_or_null_sequence.cc

@@ -13,6 +13,7 @@
 #include "base/stl_util.h"
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 
 namespace blink {
@@ -72,12 +73,18 @@ void V8DoubleOrDoubleOrNullSequence::ToImpl(
   if (conversion_mode == UnionTypeConversionMode::kNullable && IsUndefinedOrNull(v8_value))
     return;
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    Vector<base::Optional<double>> cpp_value = NativeValueTraits<IDLSequence<IDLNullable<IDLDouble>>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    impl.SetDoubleOrNullSequence(cpp_value);
-    return;
+    if (!script_iterator.IsNull()) {
+      Vector<base::Optional<double>> cpp_value = NativeValueTraits<IDLSequence<IDLNullable<IDLDouble>>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      impl.SetDoubleOrNullSequence(cpp_value);
+      return;
+    }
   }
 
   if (v8_value->IsNumber()) {
@@ -119,3 +126,4 @@ DoubleOrDoubleOrNullSequence NativeValueTraits<DoubleOrDoubleOrNullSequence>::Na
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/double_or_double_sequence.cc

@@ -13,6 +13,7 @@
 #include "base/stl_util.h"
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 
 namespace blink {
@@ -72,12 +73,18 @@ void V8DoubleOrDoubleSequence::ToImpl(
   if (conversion_mode == UnionTypeConversionMode::kNullable && IsUndefinedOrNull(v8_value))
     return;
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    Vector<double> cpp_value = NativeValueTraits<IDLSequence<IDLDouble>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    impl.SetDoubleSequence(cpp_value);
-    return;
+    if (!script_iterator.IsNull()) {
+      Vector<double> cpp_value = NativeValueTraits<IDLSequence<IDLDouble>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      impl.SetDoubleSequence(cpp_value);
+      return;
+    }
   }
 
   if (v8_value->IsNumber()) {
@@ -119,3 +126,4 @@ DoubleOrDoubleSequence NativeValueTraits<DoubleOrDoubleSequence>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/double_or_long_or_boolean_sequence.cc

@@ -14,6 +14,7 @@
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/long_or_boolean.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 
 namespace blink {
@@ -74,12 +75,18 @@ void V8DoubleOrLongOrBooleanSequence::ToImpl(
   if (conversion_mode == UnionTypeConversionMode::kNullable && IsUndefinedOrNull(v8_value))
     return;
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    HeapVector<LongOrBoolean> cpp_value = NativeValueTraits<IDLSequence<LongOrBoolean>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    impl.SetLongOrBooleanSequence(cpp_value);
-    return;
+    if (!script_iterator.IsNull()) {
+      HeapVector<LongOrBoolean> cpp_value = NativeValueTraits<IDLSequence<LongOrBoolean>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      impl.SetLongOrBooleanSequence(cpp_value);
+      return;
+    }
   }
 
   if (v8_value->IsNumber()) {
@@ -121,3 +128,4 @@ DoubleOrLongOrBooleanSequence NativeValueTraits<DoubleOrLongOrBooleanSequence>::
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/double_or_string.cc

@@ -111,3 +111,4 @@ DoubleOrString NativeValueTraits<DoubleOrString>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/double_or_string_or_double_or_string_sequence.cc

@@ -14,6 +14,7 @@
 #include "third_party/blink/renderer/bindings/core/v8/double_or_string.h"
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 
 namespace blink {
@@ -91,12 +92,18 @@ void V8DoubleOrStringOrDoubleOrStringSequence::ToImpl(
   if (conversion_mode == UnionTypeConversionMode::kNullable && IsUndefinedOrNull(v8_value))
     return;
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    HeapVector<DoubleOrString> cpp_value = NativeValueTraits<IDLSequence<DoubleOrString>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    impl.SetDoubleOrStringSequence(cpp_value);
-    return;
+    if (!script_iterator.IsNull()) {
+      HeapVector<DoubleOrString> cpp_value = NativeValueTraits<IDLSequence<DoubleOrString>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      impl.SetDoubleOrStringSequence(cpp_value);
+      return;
+    }
   }
 
   if (v8_value->IsNumber()) {
@@ -140,3 +147,4 @@ DoubleOrStringOrDoubleOrStringSequence NativeValueTraits<DoubleOrStringOrDoubleO
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/element_sequence_or_byte_string_double_or_string_record.cc

@@ -14,6 +14,7 @@
 #include "third_party/blink/renderer/bindings/core/v8/double_or_string.h"
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_element.h"
 #include "third_party/blink/renderer/core/css/cssom/element_computed_style_map.h"
@@ -81,12 +82,18 @@ void V8ElementSequenceOrByteStringDoubleOrStringRecord::ToImpl(
   if (conversion_mode == UnionTypeConversionMode::kNullable && IsUndefinedOrNull(v8_value))
     return;
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    HeapVector<Member<Element>> cpp_value = NativeValueTraits<IDLSequence<Element>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    impl.SetElementSequence(cpp_value);
-    return;
+    if (!script_iterator.IsNull()) {
+      HeapVector<Member<Element>> cpp_value = NativeValueTraits<IDLSequence<Element>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      impl.SetElementSequence(cpp_value);
+      return;
+    }
   }
 
   if (v8_value->IsObject()) {
@@ -122,3 +129,4 @@ ElementSequenceOrByteStringDoubleOrStringRecord NativeValueTraits<ElementSequenc
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/float_or_boolean.cc

@@ -116,3 +116,4 @@ FloatOrBoolean NativeValueTraits<FloatOrBoolean>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/long_or_boolean.cc

@@ -116,3 +116,4 @@ LongOrBoolean NativeValueTraits<LongOrBoolean>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/long_or_test_dictionary.cc

@@ -128,3 +128,4 @@ LongOrTestDictionary NativeValueTraits<LongOrTestDictionary>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/long_sequence_or_event.cc

@@ -13,6 +13,7 @@
 #include "base/stl_util.h"
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_event.h"
 
@@ -80,12 +81,18 @@ void V8LongSequenceOrEvent::ToImpl(
     return;
   }
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    Vector<int32_t> cpp_value = NativeValueTraits<IDLSequence<IDLLong>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    impl.SetLongSequence(cpp_value);
-    return;
+    if (!script_iterator.IsNull()) {
+      Vector<int32_t> cpp_value = NativeValueTraits<IDLSequence<IDLLong>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      impl.SetLongSequence(cpp_value);
+      return;
+    }
   }
 
   exception_state.ThrowTypeError("The provided value is not of type '(sequence<long> or Event)'");
@@ -113,3 +120,4 @@ LongSequenceOrEvent NativeValueTraits<LongSequenceOrEvent>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/nested_union_type.cc

@@ -14,6 +14,7 @@
 #include "third_party/blink/renderer/bindings/core/v8/byte_string_or_node_list.h"
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_event.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_node.h"
@@ -171,12 +172,18 @@ void V8NodeOrLongSequenceOrEventOrXMLHttpRequestOrStringOrStringByteStringOrNode
     return;
   }
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    Vector<int32_t> cpp_value = NativeValueTraits<IDLSequence<IDLLong>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    impl.SetLongSequence(cpp_value);
-    return;
+    if (!script_iterator.IsNull()) {
+      Vector<int32_t> cpp_value = NativeValueTraits<IDLSequence<IDLLong>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      impl.SetLongSequence(cpp_value);
+      return;
+    }
   }
 
   if (v8_value->IsObject()) {
@@ -226,3 +233,4 @@ NodeOrLongSequenceOrEventOrXMLHttpRequestOrStringOrStringByteStringOrNodeListRec
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/node_or_node_list.cc

@@ -115,3 +115,4 @@ NodeOrNodeList NativeValueTraits<NodeOrNodeList>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/string_or_array_buffer_or_array_buffer_view.cc

@@ -139,3 +139,4 @@ StringOrArrayBufferOrArrayBufferView NativeValueTraits<StringOrArrayBufferOrArra
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/string_or_double.cc

@@ -111,3 +111,4 @@ StringOrDouble NativeValueTraits<StringOrDouble>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/string_or_string_sequence.cc

@@ -13,6 +13,7 @@
 #include "base/stl_util.h"
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 
 namespace blink {
@@ -72,12 +73,18 @@ void V8StringOrStringSequence::ToImpl(
   if (conversion_mode == UnionTypeConversionMode::kNullable && IsUndefinedOrNull(v8_value))
     return;
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    Vector<String> cpp_value = NativeValueTraits<IDLSequence<IDLString>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    impl.SetStringSequence(cpp_value);
-    return;
+    if (!script_iterator.IsNull()) {
+      Vector<String> cpp_value = NativeValueTraits<IDLSequence<IDLString>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      impl.SetStringSequence(cpp_value);
+      return;
+    }
   }
 
   {
@@ -111,3 +118,4 @@ StringOrStringSequence NativeValueTraits<StringOrStringSequence>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/string_treat_null_as_empty_string_or_long.cc

@@ -111,3 +111,4 @@ StringTreatNullAsEmptyStringOrLong NativeValueTraits<StringTreatNullAsEmptyStrin
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/test_enum_or_double.cc

@@ -130,3 +130,4 @@ TestEnumOrDouble NativeValueTraits<TestEnumOrDouble>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/test_enum_or_test_enum_or_null_sequence.cc

@@ -13,6 +13,7 @@
 #include "base/stl_util.h"
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 
 namespace blink {
@@ -95,21 +96,28 @@ void V8TestEnumOrTestEnumOrNullSequence::ToImpl(
   if (conversion_mode == UnionTypeConversionMode::kNullable && IsUndefinedOrNull(v8_value))
     return;
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    Vector<String> cpp_value = NativeValueTraits<IDLSequence<IDLStringOrNull>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    const char* const kValidValues[] = {
-        nullptr,
-        "",
-        "EnumValue1",
-        "EnumValue2",
-        "EnumValue3",
-    };
-    if (!IsValidEnum(cpp_value, kValidValues, base::size(kValidValues), "TestEnum", exception_state))
+    if (!script_iterator.IsNull()) {
+      Vector<String> cpp_value = NativeValueTraits<IDLSequence<IDLStringOrNull>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      const char* const kValidValues[] = {
+          nullptr,
+          "",
+          "EnumValue1",
+          "EnumValue2",
+          "EnumValue3",
+      };
+      if (!IsValidEnum(cpp_value, kValidValues, base::size(kValidValues),
+                       "TestEnum", exception_state))
+        return;
+      impl.SetTestEnumOrNullSequence(cpp_value);
       return;
-    impl.SetTestEnumOrNullSequence(cpp_value);
-    return;
+    }
   }
 
   {
@@ -151,3 +159,4 @@ TestEnumOrTestEnumOrNullSequence NativeValueTraits<TestEnumOrTestEnumOrNullSeque
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/test_enum_or_test_enum_sequence.cc

@@ -13,6 +13,7 @@
 #include "base/stl_util.h"
 #include "third_party/blink/renderer/bindings/core/v8/idl_types.h"
 #include "third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h"
+#include "third_party/blink/renderer/bindings/core/v8/script_iterator.h"
 #include "third_party/blink/renderer/bindings/core/v8/to_v8_for_core.h"
 
 namespace blink {
@@ -94,20 +95,27 @@ void V8TestEnumOrTestEnumSequence::ToImpl(
   if (conversion_mode == UnionTypeConversionMode::kNullable && IsUndefinedOrNull(v8_value))
     return;
 
-  if (HasCallableIteratorSymbol(isolate, v8_value, exception_state)) {
-    Vector<String> cpp_value = NativeValueTraits<IDLSequence<IDLString>>::NativeValue(isolate, v8_value, exception_state);
+  if (v8_value->IsObject()) {
+    ScriptIterator script_iterator = ScriptIterator::FromIterable(
+        isolate, v8_value.As<v8::Object>(), exception_state);
     if (exception_state.HadException())
       return;
-    const char* const kValidValues[] = {
-        "",
-        "EnumValue1",
-        "EnumValue2",
-        "EnumValue3",
-    };
-    if (!IsValidEnum(cpp_value, kValidValues, base::size(kValidValues), "TestEnum", exception_state))
+    if (!script_iterator.IsNull()) {
+      Vector<String> cpp_value = NativeValueTraits<IDLSequence<IDLString>>::NativeValue(isolate, std::move(script_iterator), exception_state);
+      if (exception_state.HadException())
+        return;
+      const char* const kValidValues[] = {
+          "",
+          "EnumValue1",
+          "EnumValue2",
+          "EnumValue3",
+      };
+      if (!IsValidEnum(cpp_value, kValidValues, base::size(kValidValues),
+                       "TestEnum", exception_state))
+        return;
+      impl.SetTestEnumSequence(cpp_value);
       return;
-    impl.SetTestEnumSequence(cpp_value);
-    return;
+    }
   }
 
   {
@@ -149,3 +157,4 @@ TestEnumOrTestEnumSequence NativeValueTraits<TestEnumOrTestEnumSequence>::Native
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/test_interface_2_or_uint8_array.cc

@@ -112,3 +112,4 @@ TestInterface2OrUint8Array NativeValueTraits<TestInterface2OrUint8Array>::Native
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/test_interface_or_long.cc

@@ -124,3 +124,4 @@ TestInterfaceOrLong NativeValueTraits<TestInterfaceOrLong>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/test_interface_or_test_interface_empty.cc

@@ -116,3 +116,4 @@ TestInterfaceOrTestInterfaceEmpty NativeValueTraits<TestInterfaceOrTestInterface
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/unrestricted_double_or_string.cc

@@ -111,3 +111,4 @@ UnrestrictedDoubleOrString NativeValueTraits<UnrestrictedDoubleOrString>::Native
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/unsigned_long_long_or_boolean_or_test_callback_interface.cc

@@ -143,3 +143,4 @@ UnsignedLongLongOrBooleanOrTestCallbackInterface NativeValueTraits<UnsignedLongL
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/core/xml_http_request_or_string.cc

@@ -111,3 +111,4 @@ XMLHttpRequestOrString NativeValueTraits<XMLHttpRequestOrString>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/modules/boolean_or_string.cc

@@ -108,3 +108,4 @@ BooleanOrString NativeValueTraits<BooleanOrString>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/renderer/bindings/tests/results/modules/test_dictionary_or_long.cc

@@ -128,3 +128,4 @@ TestDictionaryOrLong NativeValueTraits<TestDictionaryOrLong>::NativeValue(
 }
 
 }  // namespace blink
+

third_party/blink/web_tests/bindings/idl-union-type-unittest-expected.txt

@@ -38,7 +38,7 @@ PASS unionTypesTest.doubleOrStringSequenceArg([1, "foo", "bar", 2]) is "double:
 PASS unionTypesTest.doubleOrStringSequenceArg([null, undefined, {}, []]) is "string: null, string: undefined, string: [object Object], string: "
 PASS unionTypesTest.doubleOrStringSequenceArg(null) threw exception TypeError: Failed to execute 'doubleOrStringSequenceArg' on 'UnionTypesTest': The provided value cannot be converted to a sequence..
 PASS unionTypesTest.doubleOrStringSequenceArg(undefined) threw exception TypeError: Failed to execute 'doubleOrStringSequenceArg' on 'UnionTypesTest': The provided value cannot be converted to a sequence..
-PASS unionTypesTest.doubleOrStringSequenceArg({}) threw exception TypeError: Failed to execute 'doubleOrStringSequenceArg' on 'UnionTypesTest': Iterator getter is not callable..
+PASS unionTypesTest.doubleOrStringSequenceArg({}) threw exception TypeError: Failed to execute 'doubleOrStringSequenceArg' on 'UnionTypesTest': The object must have a callable @@iterator property..
 
 
 Tests for method arguments with defaults

third_party/blink/web_tests/external/wpt/WebIDL/ecmascript-binding/sequence-conversion-expected.txt

@@ -2,6 +2,7 @@ This is a testharness.js-based test.
 PASS An array
 PASS A generator
 FAIL An array with an overridden Symbol.iterator assert_array_equals: property 0, expected 6 but got 1
+PASS An object with an overriden Symbol.iterator
 FAIL An array with an overridden Symbol.iterator on the prototype assert_array_equals: property 0, expected 11 but got 1
 FAIL An array with an overridden %ArrayIterator%.prototype.next assert_array_equals: property 0, expected 8 but got 1
 PASS A holey array with fallback to an accessor on the prototype

third_party/blink/web_tests/external/wpt/WebIDL/ecmascript-binding/sequence-conversion.html

@@ -51,6 +51,27 @@ test(() => {
   assert_equals(callCount, 1, "@@iterator must only have been gotten once");
 }, "An array with an overridden Symbol.iterator");
 
+test(t => {
+  function* generatorFunc() {
+    yield ["foo", "bar"];
+    yield ["baz", "quux"];
+  }
+
+  let callCount = 0;
+  const obj = {};
+  Object.defineProperty(obj, Symbol.iterator, {
+    get() {
+      ++callCount;
+      return generatorFunc;
+    }
+  });
+
+  const searchParams = new URLSearchParams(obj);
+  assert_equals(searchParams.get("foo"), "bar");
+  assert_equals(searchParams.get("baz"), "quux");
+  assert_equals(callCount, 1, "@@iterator must only have been gotten once");
+}, "An object with an overriden Symbol.iterator");
+
 test(t => {
   const originalIterator = Object.getOwnPropertyDescriptor(Array.prototype, Symbol.iterator);
   t.add_cleanup(() => {

third_party/blink/web_tests/fast/dom/Window/window-postmessage-args-expected.txt

@@ -4,8 +4,8 @@ Test that the second argument of window.postMessage is ignored or triggers an er
 
 PASS Posting message ('1', 1): threw exception TypeError: Failed to execute 'postMessage' on 'Window': The provided value cannot be converted to a sequence.
 PASS Posting message ('2', c): threw exception TypeError: Failed to execute 'postMessage' on 'Window': The provided value cannot be converted to a sequence.
-PASS Posting message ('3', [object Object]): threw exception TypeError: Failed to execute 'postMessage' on 'Window': Iterator getter is not callable.
-PASS Posting message ('4', [object Window]): threw exception TypeError: Failed to execute 'postMessage' on 'Window': Iterator getter is not callable.
+PASS Posting message ('3', [object Object]): threw exception TypeError: Failed to execute 'postMessage' on 'Window': The object must have a callable @@iterator property.
+PASS Posting message ('4', [object Window]): threw exception TypeError: Failed to execute 'postMessage' on 'Window': The object must have a callable @@iterator property.
 PASS Posting message ('5', undefined) did not throw an exception
 PASS Posting message ('5a', null): threw exception TypeError: Failed to execute 'postMessage' on 'Window': The provided value cannot be converted to a sequence.
 PASS Posting message ('6', undefined) did not throw an exception
@@ -25,7 +25,7 @@ PASS Posting message ('[object ArrayBuffer]', ): threw exception DataCloneError:
 PASS Posting message ('data', [object ArrayBuffer]): threw exception DataCloneError: Failed to execute 'postMessage' on 'Window': ArrayBuffer at index 0 is already detached.
 PASS Posting message ('[detached TypedArray]', ): threw exception DataCloneError: Failed to execute 'postMessage' on 'Window': An ArrayBuffer is detached and could not be cloned.
 PASS Posting message ('data', [detached TypedArray]): threw exception TypeError: Failed to execute 'postMessage' on 'Window': Value at index 0 does not have a transferable type.
-PASS Posting message ('data', [object Object]): threw exception TypeError: Failed to execute 'postMessage' on 'Window': Iterator getter is not callable.
+PASS Posting message ('data', [object Object]): threw exception TypeError: Failed to execute 'postMessage' on 'Window': The object must have a callable @@iterator property.
 PASS Posting message ('data', 1,,2): threw exception TypeError: Failed to execute 'postMessage' on 'Window': Value at index 0 does not have a transferable type.
 PASS Posting message ('data', ,function postMessage() { [native code] }): threw exception TypeError: Failed to execute 'postMessage' on 'Window': Value at index 0 is an untransferable 'null' value.
 PASS window.postMessage() threw exception TypeError: Failed to execute 'postMessage' on 'Window': 1 argument required, but only 0 present..

third_party/blink/web_tests/fast/events/constructors/message-event-constructor-expected.txt

@@ -82,8 +82,8 @@ PASS new MessageEvent('eventType', { ports: [channel.port1, channel.port2, chann
 PASS new MessageEvent('eventType', { ports: [] }).ports is []
 PASS new MessageEvent('eventType', { ports: undefined }).ports is []
 PASS new MessageEvent('eventType', { ports: [1, 2, 3] }).ports[2] threw exception TypeError: Failed to construct 'MessageEvent': Failed to convert value to 'MessagePort'..
-PASS new MessageEvent('eventType', { ports: test_object }).ports threw exception TypeError: Failed to construct 'MessageEvent': Iterator getter is not callable..
-PASS new MessageEvent('eventType', { ports: document }).ports threw exception TypeError: Failed to construct 'MessageEvent': Iterator getter is not callable..
+PASS new MessageEvent('eventType', { ports: test_object }).ports threw exception TypeError: Failed to construct 'MessageEvent': The object must have a callable @@iterator property..
+PASS new MessageEvent('eventType', { ports: document }).ports threw exception TypeError: Failed to construct 'MessageEvent': The object must have a callable @@iterator property..
 PASS new MessageEvent('eventType', { ports: false }).ports threw exception TypeError: Failed to construct 'MessageEvent': The provided value cannot be converted to a sequence..
 PASS new MessageEvent('eventType', { ports: true }).ports threw exception TypeError: Failed to construct 'MessageEvent': The provided value cannot be converted to a sequence..
 PASS new MessageEvent('eventType', { ports: '' }).ports threw exception TypeError: Failed to construct 'MessageEvent': The provided value cannot be converted to a sequence..
@@ -94,8 +94,8 @@ PASS new MessageEvent('eventType', { ports: NaN }).ports threw exception TypeErr
 PASS new MessageEvent('eventType', { get ports() { return 123; } }).ports threw exception TypeError: Failed to construct 'MessageEvent': The provided value cannot be converted to a sequence..
 PASS new MessageEvent('eventType', { get ports() { throw 'MessageEvent Error'; } }) threw exception MessageEvent Error.
 PASS new MessageEvent('eventType', { ports: null }).ports threw exception TypeError: Failed to construct 'MessageEvent': The provided value cannot be converted to a sequence..
-PASS new MessageEvent('eventType', { ports: {valueOf: function () { return [channel.port1, channel.port2, channel.port2]; } } }).ports[0] threw exception TypeError: Failed to construct 'MessageEvent': Iterator getter is not callable..
-PASS new MessageEvent('eventType', { bubbles: true, cancelable: true, data: test_object, origin: 'wonderful', lastEventId: 'excellent', source: window, ports: {length: 3, 0: channel.port1, 1: channel.port2, 2: channel2.port1} }).ports[2] threw exception TypeError: Failed to construct 'MessageEvent': Iterator getter is not callable..
+PASS new MessageEvent('eventType', { ports: {valueOf: function () { return [channel.port1, channel.port2, channel.port2]; } } }).ports[0] threw exception TypeError: Failed to construct 'MessageEvent': The object must have a callable @@iterator property..
+PASS new MessageEvent('eventType', { bubbles: true, cancelable: true, data: test_object, origin: 'wonderful', lastEventId: 'excellent', source: window, ports: {length: 3, 0: channel.port1, 1: channel.port2, 2: channel2.port1} }).ports[2] threw exception TypeError: Failed to construct 'MessageEvent': The object must have a callable @@iterator property..
 PASS new MessageEvent('eventType', { bubbles: true, cancelable: true, data: test_object, origin: 'wonderful', lastEventId: 'excellent', source: window, ports: [channel.port1, channel.port2, channel2.port1] }).bubbles is true
 PASS new MessageEvent('eventType', { bubbles: true, cancelable: true, data: test_object, origin: 'wonderful', lastEventId: 'excellent', source: window, ports: [channel.port1, channel.port2, channel2.port1] }).cancelable is true
 PASS new MessageEvent('eventType', { bubbles: true, cancelable: true, data: test_object, origin: 'wonderful', lastEventId: 'excellent', source: window, ports: [channel.port1, channel.port2, channel2.port1] }).data is test_object

third_party/blink/web_tests/fast/events/init-message-event-expected.txt

@@ -2,7 +2,7 @@ Checks that initMessageEvent() is working
 
 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
-PASS newEvent.initMessageEvent("message", true, true, "ff", "*", 43, window, {x:1}); threw exception TypeError: Failed to execute 'initMessageEvent' on 'MessageEvent': Iterator getter is not callable..
+PASS newEvent.initMessageEvent("message", true, true, "ff", "*", 43, window, {x:1}); threw exception TypeError: Failed to execute 'initMessageEvent' on 'MessageEvent': The object must have a callable @@iterator property..
 PASS newEvent.initMessageEvent("message", true, true, "ff", "*", 43, window, undefined) did not throw exception.
 PASS [object MessageEvent] is an instance of function MessageEvent() { [native code] }
 PASS successfullyParsed is true

third_party/blink/web_tests/fast/events/init-message-event.html

@@ -11,7 +11,7 @@ description("Checks that initMessageEvent() is working");
 var newEvent;
 function runTest() {
     newEvent = document.createEvent("MessageEvent");
-    shouldThrow('newEvent.initMessageEvent("message", true, true, "ff", "*", 43, window, {x:1});', '"TypeError: Failed to execute \'initMessageEvent\' on \'MessageEvent\': Iterator getter is not callable."');
+    shouldThrow('newEvent.initMessageEvent("message", true, true, "ff", "*", 43, window, {x:1});', '"TypeError: Failed to execute \'initMessageEvent\' on \'MessageEvent\': The object must have a callable @@iterator property."');
     shouldNotThrow('newEvent.initMessageEvent("message", true, true, "ff", "*", 43, window, undefined)');
     shouldBeType(newEvent, MessageEvent);
 }