Reuse the TryCatch scope whe retrieving custom element properties.

Defining a custom element retrieves various properties. Previously
each retrieval used a separate TryCatch, which turns out to be
expensive. This makes them reuse a single TryCatch.

Bug: 710184
Change-Id: Ieadd5ba9c9197fd4a4a0b6b1faf3861d1df53f3b
Reviewed-on: https://chromium-review.googlesource.com/520962Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Dominic Cooney <dominicc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#476542}

third_party/WebKit/Source/bindings/core/v8/ScriptCustomElementDefinitionBuilder.cpp

@@ -56,23 +56,27 @@ bool ScriptCustomElementDefinitionBuilder::CheckConstructorNotRegistered() {
 }
 
 bool ScriptCustomElementDefinitionBuilder::ValueForName(
+    v8::Isolate* isolate,
+    v8::Local<v8::Context>& context,
+    const v8::TryCatch& try_catch,
     const v8::Local<v8::Object>& object,
     const StringView& name,
     v8::Local<v8::Value>& value) const {
-  v8::Isolate* isolate = script_state_->GetIsolate();
-  v8::Local<v8::Context> context = script_state_->GetContext();
   v8::Local<v8::String> name_string = V8AtomicString(isolate, name);
-  v8::TryCatch try_catch(isolate);
   if (!object->Get(context, name_string).ToLocal(&value)) {
     exception_state_.RethrowV8Exception(try_catch.Exception());
     return false;
   }
-  return true;
+  return script_state_->ContextIsValid();
 }
 
 bool ScriptCustomElementDefinitionBuilder::CheckPrototype() {
+  v8::Isolate* isolate = script_state_->GetIsolate();
+  v8::Local<v8::Context> context = script_state_->GetContext();
+  v8::TryCatch try_catch(isolate);
   v8::Local<v8::Value> prototype_value;
-  if (!ValueForName(constructor_, "prototype", prototype_value))
+  if (!ValueForName(isolate, context, try_catch, constructor_, "prototype",
+                    prototype_value))
     return false;
   if (!prototype_value->IsObject()) {
     exception_state_.ThrowTypeError("constructor prototype is not an object");
@@ -85,10 +89,13 @@ bool ScriptCustomElementDefinitionBuilder::CheckPrototype() {
 }
 
 bool ScriptCustomElementDefinitionBuilder::CallableForName(
+    v8::Isolate* isolate,
+    v8::Local<v8::Context>& context,
+    const v8::TryCatch& try_catch,
     const StringView& name,
     v8::Local<v8::Function>& callback) const {
   v8::Local<v8::Value> value;
-  if (!ValueForName(prototype_, name, value))
+  if (!ValueForName(isolate, context, try_catch, prototype_, name, value))
     return false;
   // "undefined" means "omitted", which is valid.
   if (value->IsUndefined())
@@ -102,16 +109,19 @@ bool ScriptCustomElementDefinitionBuilder::CallableForName(
   return true;
 }
 
-bool ScriptCustomElementDefinitionBuilder::RetrieveObservedAttributes() {
+bool ScriptCustomElementDefinitionBuilder::RetrieveObservedAttributes(
+    v8::Isolate* isolate,
+    v8::Local<v8::Context>& context,
+    const v8::TryCatch& try_catch) {
   v8::Local<v8::Value> observed_attributes_value;
-  if (!ValueForName(constructor_, "observedAttributes",
-                    observed_attributes_value))
+  if (!ValueForName(isolate, context, try_catch, constructor_,
+                    "observedAttributes", observed_attributes_value))
     return false;
   if (observed_attributes_value->IsUndefined())
     return true;
   Vector<String> list = NativeValueTraits<IDLSequence<IDLString>>::NativeValue(
-      script_state_->GetIsolate(), observed_attributes_value, exception_state_);
-  if (exception_state_.HadException())
+      isolate, observed_attributes_value, exception_state_);
+  if (exception_state_.HadException() || !script_state_->ContextIsValid())
     return false;
   if (list.IsEmpty())
     return true;
@@ -124,13 +134,20 @@ bool ScriptCustomElementDefinitionBuilder::RetrieveObservedAttributes() {
 bool ScriptCustomElementDefinitionBuilder::RememberOriginalProperties() {
   // Spec requires to use values of these properties at the point
   // CustomElementDefinition is built, even if JS changes them afterwards.
-  return CallableForName("connectedCallback", connected_callback_) &&
-         CallableForName("disconnectedCallback", disconnected_callback_) &&
-         CallableForName("adoptedCallback", adopted_callback_) &&
-         CallableForName("attributeChangedCallback",
+  v8::Isolate* isolate = script_state_->GetIsolate();
+  v8::Local<v8::Context> context = script_state_->GetContext();
+  v8::TryCatch try_catch(isolate);
+  return CallableForName(isolate, context, try_catch, "connectedCallback",
+                         connected_callback_) &&
+         CallableForName(isolate, context, try_catch, "disconnectedCallback",
+                         disconnected_callback_) &&
+         CallableForName(isolate, context, try_catch, "adoptedCallback",
+                         adopted_callback_) &&
+         CallableForName(isolate, context, try_catch,
+                         "attributeChangedCallback",
                          attribute_changed_callback_) &&
          (attribute_changed_callback_.IsEmpty() ||
-          RetrieveObservedAttributes());
+          RetrieveObservedAttributes(isolate, context, try_catch));
 }
 
 CustomElementDefinition* ScriptCustomElementDefinitionBuilder::Build(

third_party/WebKit/Source/bindings/core/v8/ScriptCustomElementDefinitionBuilder.h

@@ -59,11 +59,20 @@ class CORE_EXPORT ScriptCustomElementDefinitionBuilder
   HashSet<AtomicString> observed_attributes_;
   ExceptionState& exception_state_;
 
-  bool ValueForName(const v8::Local<v8::Object>&,
+  bool ValueForName(v8::Isolate*,
+                    v8::Local<v8::Context>&,
+                    const v8::TryCatch&,
+                    const v8::Local<v8::Object>&,
                     const StringView&,
                     v8::Local<v8::Value>&) const;
-  bool CallableForName(const StringView&, v8::Local<v8::Function>&) const;
-  bool RetrieveObservedAttributes();
+  bool CallableForName(v8::Isolate*,
+                       v8::Local<v8::Context>&,
+                       const v8::TryCatch&,
+                       const StringView&,
+                       v8::Local<v8::Function>&) const;
+  bool RetrieveObservedAttributes(v8::Isolate*,
+                                  v8::Local<v8::Context>&,
+                                  const v8::TryCatch&);
 };
 
 }  // namespace blink