[css-properties-values-api] Support composite for custom property lists.

This CL implements CSSCustomListInterpolationType::Composite by adapting
the callback passed to ListInterpolationFunctions to the Composite
function of the inner interpolation type.

For the current set of supported syntaxes, only <length-percentage>
uses non-interpolable values. This CL adds a
NonInterpolableValuesAreCompatibleCallback which DCHECKs that we don't
have any non-interpolable values (except for <length-percentage>).
This ensures that we don't forget to update this function if we add
support for new types to css-properties-values-api in the future.

Bug: 981024
Change-Id: Iccaaa779a2de0446a7bf9823cdb3e42161b07f26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1688832
Commit-Queue: Anders Hartvoll Ruud <andruud@chromium.org>
Reviewed-by: Robert Flack <flackr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682700}

third_party/blink/renderer/core/animation/css_custom_list_interpolation_type.cc

@@ -94,9 +94,43 @@ void CSSCustomListInterpolationType::Composite(
     double underlying_fraction,
     const InterpolationValue& value,
     double interpolation_fraction) const {
-  // TODO(andruud): Properly support composition once behavior is defined.
-  // https://github.com/w3c/css-houdini-drafts/issues/799
-  underlying_value_owner.Set(*this, value);
+  // This adapts a ListInterpolationFunctions::CompositeItemCallback function
+  // such that we can use the InterpolationType::Composite function of the
+  // inner interpolation type to get the answer.
+  //
+  // TODO(andruud): Make InterpolationType::Composite take an UnderlyingValue
+  // rather than an UnderlyingValueOwner.
+  auto composite_callback =
+      [](const CSSInterpolationType* interpolation_type,
+         double interpolation_fraction, UnderlyingValue& underlying_value,
+         double underlying_fraction,
+         const InterpolableValue& interpolable_value,
+         const NonInterpolableValue* non_interpolable_value) {
+        UnderlyingValueOwner owner;
+        owner.Set(*interpolation_type,
+                  InterpolationValue(
+                      underlying_value.MutableInterpolableValue().Clone(),
+                      underlying_value.GetNonInterpolableValue()));
+
+        InterpolationValue interpolation_value(interpolable_value.Clone(),
+                                               non_interpolable_value);
+        interpolation_type->Composite(owner, underlying_fraction,
+                                      interpolation_value,
+                                      interpolation_fraction);
+
+        underlying_value.SetInterpolableValue(
+            owner.Value().Clone().interpolable_value);
+        underlying_value.SetNonInterpolableValue(
+            owner.GetNonInterpolableValue());
+      };
+
+  ListInterpolationFunctions::Composite(
+      underlying_value_owner, underlying_fraction, *this, value,
+      ListInterpolationFunctions::LengthMatchingStrategy::kEqual,
+      GetNonInterpolableValuesAreCompatibleCallback(),
+      WTF::BindRepeating(composite_callback,
+                         WTF::Unretained(inner_interpolation_type_.get()),
+                         interpolation_fraction));
 }
 
 PairwiseInterpolationValue CSSCustomListInterpolationType::MaybeMergeSingles(
@@ -109,4 +143,23 @@ PairwiseInterpolationValue CSSCustomListInterpolationType::MaybeMergeSingles(
                          WTF::Unretained(inner_interpolation_type_.get())));
 }
 
+static bool VerifyNoNonInterpolableValues(const NonInterpolableValue* a,
+                                          const NonInterpolableValue* b) {
+  DCHECK(!a && !b);
+  return true;
+}
+
+ListInterpolationFunctions::NonInterpolableValuesAreCompatibleCallback
+CSSCustomListInterpolationType::GetNonInterpolableValuesAreCompatibleCallback()
+    const {
+  if (syntax_type_ == CSSSyntaxType::kLengthPercentage) {
+    return WTF::BindRepeating(
+        LengthInterpolationFunctions::NonInterpolableValuesAreCompatible);
+  }
+  // TODO(https://crbug.com/981537): Add support for <image> here.
+  // TODO(https://crbug.com/981538): Add support for <transform-function> here.
+  // TODO(https://crbug.com/981542): Add support for <transform-list> here.
+  return WTF::BindRepeating(VerifyNoNonInterpolableValues);
+}
+
 }  // namespace blink

third_party/blink/renderer/core/animation/css_custom_list_interpolation_type.h

@@ -18,9 +18,11 @@ class CSSCustomListInterpolationType : public CSSInterpolationType {
       PropertyHandle property,
       const PropertyRegistration* registration,
       std::unique_ptr<CSSInterpolationType> inner_interpolation_type,
+      CSSSyntaxType syntax_type,
       CSSSyntaxRepeat syntax_repeat)
       : CSSInterpolationType(property, registration),
         inner_interpolation_type_(std::move(inner_interpolation_type)),
+        syntax_type_(syntax_type),
         syntax_repeat_(syntax_repeat) {
     DCHECK(property.IsCSSCustomProperty());
   }
@@ -66,6 +68,9 @@ class CSSCustomListInterpolationType : public CSSInterpolationType {
     return nullptr;
   }
 
+  ListInterpolationFunctions::NonInterpolableValuesAreCompatibleCallback
+  GetNonInterpolableValuesAreCompatibleCallback() const;
+
   // This InterpolationType represents the interpolation of elements inside
   // the list.
   //
@@ -77,6 +82,7 @@ class CSSCustomListInterpolationType : public CSSInterpolationType {
   // InterpolationType::Apply on inner_interpolation_type_.
   std::unique_ptr<CSSInterpolationType> inner_interpolation_type_;
 
+  const CSSSyntaxType syntax_type_;
   const CSSSyntaxRepeat syntax_repeat_;
 };
 

third_party/blink/renderer/core/animation/css_interpolation_types_map.cc

@@ -447,7 +447,7 @@ CSSInterpolationTypesMap::CreateInterpolationTypesForCSSSyntax(
     if (component.IsRepeatable()) {
       interpolation_type = std::make_unique<CSSCustomListInterpolationType>(
           property, &registration, std::move(interpolation_type),
-          component.GetRepeat());
+          component.GetType(), component.GetRepeat());
     }
 
     result.push_back(std::move(interpolation_type));

third_party/blink/renderer/core/animation/css_text_indent_interpolation_type.cc

@@ -87,6 +87,11 @@ class UnderlyingTextIndentAsLengthValue : public UnderlyingValue {
     return inner_underlying_value_.MutableInterpolableValue();
   }
 
+  void SetInterpolableValue(
+      std::unique_ptr<InterpolableValue> interpolable_value) final {
+    inner_underlying_value_.SetInterpolableValue(std::move(interpolable_value));
+  }
+
   const NonInterpolableValue* GetNonInterpolableValue() const final {
     const auto& text_indent_non_interpolable_value =
         ToCSSTextIndentNonInterpolableValue(

third_party/blink/renderer/core/animation/list_interpolation_functions.cc

@@ -35,6 +35,11 @@ class UnderlyingItemValue : public UnderlyingValue {
     return *ToInterpolableList(underlying_list_.MutableInterpolableValue())
                 .GetMutable(index_);
   }
+  void SetInterpolableValue(
+      std::unique_ptr<InterpolableValue> interpolable_value) final {
+    ToInterpolableList(underlying_list_.MutableInterpolableValue())
+        .Set(index_, std::move(interpolable_value));
+  }
   const NonInterpolableValue* GetNonInterpolableValue() const final {
     return ToNonInterpolableList(*underlying_list_.GetNonInterpolableValue())
         .Get(index_);

third_party/blink/renderer/core/animation/list_interpolation_functions_test.cc

@@ -55,6 +55,11 @@ class TestUnderlyingValue : public UnderlyingValue {
     return *interpolation_value_.interpolable_value;
   }
 
+  void SetInterpolableValue(
+      std::unique_ptr<InterpolableValue> interpolable_value) final {
+    interpolation_value_.interpolable_value = std::move(interpolable_value);
+  }
+
   const NonInterpolableValue* GetNonInterpolableValue() const final {
     return interpolation_value_.non_interpolable_value.get();
   }

third_party/blink/renderer/core/animation/size_interpolation_functions.cc

@@ -74,6 +74,11 @@ class UnderlyingSizeAsLengthValue : public UnderlyingValue {
     return inner_underlying_value_.MutableInterpolableValue();
   }
 
+  void SetInterpolableValue(
+      std::unique_ptr<InterpolableValue> interpolable_value) final {
+    inner_underlying_value_.SetInterpolableValue(std::move(interpolable_value));
+  }
+
   const NonInterpolableValue* GetNonInterpolableValue() const final {
     const auto& size_non_interpolable_value = ToCSSSizeNonInterpolableValue(
         *inner_underlying_value_.GetNonInterpolableValue());

third_party/blink/renderer/core/animation/underlying_value.h

@@ -24,6 +24,8 @@ class CORE_EXPORT UnderlyingValue {
  public:
   virtual InterpolableValue& MutableInterpolableValue() = 0;
 
+  virtual void SetInterpolableValue(std::unique_ptr<InterpolableValue>) = 0;
+
   virtual const NonInterpolableValue* GetNonInterpolableValue() const = 0;
 
   // The NonInterpolableValue part of the underlying value may not be mutated,

third_party/blink/renderer/core/animation/underlying_value_owner.cc

@@ -17,6 +17,12 @@ InterpolableValue& UnderlyingValueOwner::MutableInterpolableValue() {
   return *MutableValue().interpolable_value;
 }
 
+void UnderlyingValueOwner::SetInterpolableValue(
+    std::unique_ptr<InterpolableValue> interpolable_value) {
+  DCHECK(type_);
+  MutableValue().interpolable_value = std::move(interpolable_value);
+}
+
 const NonInterpolableValue* UnderlyingValueOwner::GetNonInterpolableValue()
     const {
   DCHECK(value_);

third_party/blink/renderer/core/animation/underlying_value_owner.h

@@ -33,6 +33,7 @@ class CORE_EXPORT UnderlyingValueOwner : public UnderlyingValue {
 
   // UnderlyingValue
   InterpolableValue& MutableInterpolableValue() final;
+  void SetInterpolableValue(std::unique_ptr<InterpolableValue>) final;
   const NonInterpolableValue* GetNonInterpolableValue() const final;
   void SetNonInterpolableValue(scoped_refptr<const NonInterpolableValue>) final;
 

third_party/blink/web_tests/animations/custom-properties/custom-angle-list-type-interpolation.html

@@ -90,10 +90,6 @@ assertInterpolation({
   {at: 1.5, is: '540deg 540deg'}
 ]);
 
-// Composition and neutralKeyframe tests assume that composite:add means
-// component-wise addition, which may or may not be the behavior we want.
-// https://github.com/w3c/css-houdini-drafts/issues/799
-
 assertInterpolation({
   property: '--angle-list',
   from: neutralKeyframe,

third_party/blink/web_tests/animations/custom-properties/custom-color-list-type-interpolation-expected.txt

@@ -45,11 +45,11 @@ PASS CSS Animations: property <--color-list> from [hsl(120, 100%, 50%) coral] to
 PASS CSS Animations: property <--color-list> from [hsl(120, 100%, 50%) coral] to [navy hsl(240, 100%, 50%)] at (0.5) is [rgb(0, 128, 64) rgb(128, 64, 168)]
 PASS CSS Animations: property <--color-list> from [hsl(120, 100%, 50%) coral] to [navy hsl(240, 100%, 50%)] at (1) is [rgb(0, 0, 128) rgb(0, 0, 255)]
 PASS CSS Animations: property <--color-list> from [hsl(120, 100%, 50%) coral] to [navy hsl(240, 100%, 50%)] at (1.5) is [rgb(0, 0, 192) rgb(0, 0, 255)]
-FAIL CSS Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (-0.3) is [rgba(0, 0, 0, 0) rgba(0, 0, 0, 0)] assert_equals: expected "rgb ( 52 , 40 , 40 ) rgb ( 104 , 104 , 104 ) " but got "rgba ( 0 , 0 , 0 , 0 ) rgba ( 0 , 0 , 0 , 0 ) "
-FAIL CSS Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (0) is [rgba(0, 0, 0, 0) rgba(0, 0, 0, 0)] assert_equals: expected "rgb ( 40 , 40 , 40 ) rgb ( 80 , 80 , 80 ) " but got "rgba ( 0 , 0 , 0 , 0 ) rgba ( 0 , 0 , 0 , 0 ) "
-FAIL CSS Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (0.5) is [rgba(0, 40, 40, 0.5) rgba(0, 0, 0, 0.5)] assert_equals: expected "rgb ( 20 , 40 , 40 ) rgb ( 40 , 40 , 40 ) " but got "rgba ( 0 , 40 , 40 , 0.5 ) rgba ( 0 , 0 , 0 , 0.5 ) "
+PASS CSS Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (-0.3) is [rgb(52, 40, 40) rgb(104, 104, 104)]
+PASS CSS Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (0) is [rgb(40, 40, 40) rgb(80, 80, 80)]
+PASS CSS Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (0.5) is [rgb(20, 40, 40) rgb(40, 40, 40)]
 PASS CSS Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (1) is [rgb(0, 40, 40) rgb(0, 0, 0)]
-FAIL CSS Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (1.5) is [rgb(0, 60, 60) rgb(0, 0, 0)] assert_equals: expected "rgb ( 0 , 40 , 40 ) rgb ( 0 , 0 , 0 ) " but got "rgb ( 0 , 60 , 60 ) rgb ( 0 , 0 , 0 ) "
+PASS CSS Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (1.5) is [rgb(0, 40, 40) rgb(0, 0, 0)]
 PASS Web Animations: property <--color-list> from [initial] to [blue red] at (-0.3) is [rgb(255, 0, 0) rgb(0, 0, 255)]
 PASS Web Animations: property <--color-list> from [initial] to [blue red] at (0) is [rgb(255, 0, 0) rgb(0, 0, 255)]
 PASS Web Animations: property <--color-list> from [initial] to [blue red] at (0.5) is [rgb(128, 0, 128) rgb(128, 0, 128)]
@@ -70,20 +70,20 @@ PASS Web Animations: property <--color-list> from [hsl(120, 100%, 50%) coral] to
 PASS Web Animations: property <--color-list> from [hsl(120, 100%, 50%) coral] to [navy hsl(240, 100%, 50%)] at (0.5) is [rgb(0, 128, 64) rgb(128, 64, 168)]
 PASS Web Animations: property <--color-list> from [hsl(120, 100%, 50%) coral] to [navy hsl(240, 100%, 50%)] at (1) is [rgb(0, 0, 128) rgb(0, 0, 255)]
 PASS Web Animations: property <--color-list> from [hsl(120, 100%, 50%) coral] to [navy hsl(240, 100%, 50%)] at (1.5) is [rgb(0, 0, 192) rgb(0, 0, 255)]
-FAIL Web Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (-0.3) is [rgba(0, 0, 0, 0) rgba(0, 0, 0, 0)] assert_equals: expected "rgb ( 52 , 40 , 40 ) rgb ( 104 , 104 , 104 ) " but got "rgba ( 0 , 0 , 0 , 0 ) rgba ( 0 , 0 , 0 , 0 ) "
-FAIL Web Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (0) is [rgba(0, 0, 0, 0) rgba(0, 0, 0, 0)] assert_equals: expected "rgb ( 40 , 40 , 40 ) rgb ( 80 , 80 , 80 ) " but got "rgba ( 0 , 0 , 0 , 0 ) rgba ( 0 , 0 , 0 , 0 ) "
-FAIL Web Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (0.5) is [rgba(0, 40, 40, 0.5) rgba(0, 0, 0, 0.5)] assert_equals: expected "rgb ( 20 , 40 , 40 ) rgb ( 40 , 40 , 40 ) " but got "rgba ( 0 , 40 , 40 , 0.5 ) rgba ( 0 , 0 , 0 , 0.5 ) "
+PASS Web Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (-0.3) is [rgb(52, 40, 40) rgb(104, 104, 104)]
+PASS Web Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (0) is [rgb(40, 40, 40) rgb(80, 80, 80)]
+PASS Web Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (0.5) is [rgb(20, 40, 40) rgb(40, 40, 40)]
 PASS Web Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (1) is [rgb(0, 40, 40) rgb(0, 0, 0)]
-FAIL Web Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (1.5) is [rgb(0, 60, 60) rgb(0, 0, 0)] assert_equals: expected "rgb ( 0 , 40 , 40 ) rgb ( 0 , 0 , 0 ) " but got "rgb ( 0 , 60 , 60 ) rgb ( 0 , 0 , 0 ) "
-FAIL Compositing: property <--color-list> underlying [darkslategray rgb(10, 10, 10)] from add [rgb(10, 10, 10) navy] to add [rgb(30, 30, 30) teal] at (-0.3) is [rgb(4, 4, 4) rgb(0, 0, 128)] assert_equals: expected "rgb ( 51 , 83 , 83 ) rgb ( 10 , 0 , 138 ) " but got "rgb ( 4 , 4 , 4 ) rgb ( 0 , 0 , 128 ) "
-FAIL Compositing: property <--color-list> underlying [darkslategray rgb(10, 10, 10)] from add [rgb(10, 10, 10) navy] to add [rgb(30, 30, 30) teal] at (0) is [rgb(10, 10, 10) rgb(0, 0, 128)] assert_equals: expected "rgb ( 57 , 89 , 89 ) rgb ( 10 , 10 , 138 ) " but got "rgb ( 10 , 10 , 10 ) rgb ( 0 , 0 , 128 ) "
-FAIL Compositing: property <--color-list> underlying [darkslategray rgb(10, 10, 10)] from add [rgb(10, 10, 10) navy] to add [rgb(30, 30, 30) teal] at (0.5) is [rgb(20, 20, 20) rgb(0, 64, 128)] assert_equals: expected "rgb ( 67 , 99 , 99 ) rgb ( 10 , 74 , 138 ) " but got "rgb ( 20 , 20 , 20 ) rgb ( 0 , 64 , 128 ) "
-FAIL Compositing: property <--color-list> underlying [darkslategray rgb(10, 10, 10)] from add [rgb(10, 10, 10) navy] to add [rgb(30, 30, 30) teal] at (1) is [rgb(30, 30, 30) rgb(0, 128, 128)] assert_equals: expected "rgb ( 77 , 109 , 109 ) rgb ( 10 , 138 , 138 ) " but got "rgb ( 30 , 30 , 30 ) rgb ( 0 , 128 , 128 ) "
-FAIL Compositing: property <--color-list> underlying [darkslategray rgb(10, 10, 10)] from add [rgb(10, 10, 10) navy] to add [rgb(30, 30, 30) teal] at (1.5) is [rgb(40, 40, 40) rgb(0, 192, 128)] assert_equals: expected "rgb ( 87 , 119 , 119 ) rgb ( 10 , 202 , 138 ) " but got "rgb ( 40 , 40 , 40 ) rgb ( 0 , 192 , 128 ) "
-FAIL Compositing: property <--color-list> underlying [gold rgb(100, 100, 100)] from add [navy rgb(0, 0, 0)] to replace [rgb(17, 17, 17) rgb(1, 1, 1)] at (-0.3) is [rgb(0, 0, 161) rgb(0, 0, 0)] assert_equals: expected "rgb ( 255 , 255 , 161 ) rgb ( 130 , 130 , 130 ) " but got "rgb ( 0 , 0 , 161 ) rgb ( 0 , 0 , 0 ) "
-FAIL Compositing: property <--color-list> underlying [gold rgb(100, 100, 100)] from add [navy rgb(0, 0, 0)] to replace [rgb(17, 17, 17) rgb(1, 1, 1)] at (0) is [rgb(0, 0, 128) rgb(0, 0, 0)] assert_equals: expected "rgb ( 255 , 215 , 128 ) rgb ( 100 , 100 , 100 ) " but got "rgb ( 0 , 0 , 128 ) rgb ( 0 , 0 , 0 ) "
-FAIL Compositing: property <--color-list> underlying [gold rgb(100, 100, 100)] from add [navy rgb(0, 0, 0)] to replace [rgb(17, 17, 17) rgb(1, 1, 1)] at (0.5) is [rgb(9, 9, 73) rgb(1, 1, 1)] assert_equals: expected "rgb ( 136 , 116 , 73 ) rgb ( 51 , 51 , 51 ) " but got "rgb ( 9 , 9 , 73 ) rgb ( 1 , 1 , 1 ) "
+PASS Web Animations: property <--color-list> from neutral to [rgb(0, 40, 40) black] at (1.5) is [rgb(0, 40, 40) rgb(0, 0, 0)]
+PASS Compositing: property <--color-list> underlying [darkslategray rgb(10, 10, 10)] from add [rgb(10, 10, 10) navy] to add [rgb(30, 30, 30) teal] at (-0.3) is [rgb(51, 83, 83) rgb(10, 0, 138)]
+PASS Compositing: property <--color-list> underlying [darkslategray rgb(10, 10, 10)] from add [rgb(10, 10, 10) navy] to add [rgb(30, 30, 30) teal] at (0) is [rgb(57, 89, 89) rgb(10, 10, 138)]
+PASS Compositing: property <--color-list> underlying [darkslategray rgb(10, 10, 10)] from add [rgb(10, 10, 10) navy] to add [rgb(30, 30, 30) teal] at (0.5) is [rgb(67, 99, 99) rgb(10, 74, 138)]
+PASS Compositing: property <--color-list> underlying [darkslategray rgb(10, 10, 10)] from add [rgb(10, 10, 10) navy] to add [rgb(30, 30, 30) teal] at (1) is [rgb(77, 109, 109) rgb(10, 138, 138)]
+PASS Compositing: property <--color-list> underlying [darkslategray rgb(10, 10, 10)] from add [rgb(10, 10, 10) navy] to add [rgb(30, 30, 30) teal] at (1.5) is [rgb(87, 119, 119) rgb(10, 202, 138)]
+PASS Compositing: property <--color-list> underlying [gold rgb(100, 100, 100)] from add [navy rgb(0, 0, 0)] to replace [rgb(17, 17, 17) rgb(1, 1, 1)] at (-0.3) is [rgb(255, 255, 161) rgb(130, 130, 130)]
+PASS Compositing: property <--color-list> underlying [gold rgb(100, 100, 100)] from add [navy rgb(0, 0, 0)] to replace [rgb(17, 17, 17) rgb(1, 1, 1)] at (0) is [rgb(255, 215, 128) rgb(100, 100, 100)]
+PASS Compositing: property <--color-list> underlying [gold rgb(100, 100, 100)] from add [navy rgb(0, 0, 0)] to replace [rgb(17, 17, 17) rgb(1, 1, 1)] at (0.5) is [rgb(136, 116, 73) rgb(51, 51, 51)]
 PASS Compositing: property <--color-list> underlying [gold rgb(100, 100, 100)] from add [navy rgb(0, 0, 0)] to replace [rgb(17, 17, 17) rgb(1, 1, 1)] at (1) is [rgb(17, 17, 17) rgb(1, 1, 1)]
-FAIL Compositing: property <--color-list> underlying [gold rgb(100, 100, 100)] from add [navy rgb(0, 0, 0)] to replace [rgb(17, 17, 17) rgb(1, 1, 1)] at (1.5) is [rgb(26, 26, 0) rgb(2, 2, 2)] assert_equals: expected "rgb ( 0 , 0 , 0 ) rgb ( 0 , 0 , 0 ) " but got "rgb ( 26 , 26 , 0 ) rgb ( 2 , 2 , 2 ) "
+FAIL Compositing: property <--color-list> underlying [gold rgb(100, 100, 100)] from add [navy rgb(0, 0, 0)] to replace [rgb(17, 17, 17) rgb(1, 1, 1)] at (1.5) is [rgba(0, 0, 0, 0.5) rgba(0, 0, 0, 0.5)] assert_equals: expected "rgb ( 0 , 0 , 0 ) rgb ( 0 , 0 , 0 ) " but got "rgba ( 0 , 0 , 0 , 0.5 ) rgba ( 0 , 0 , 0 , 0.5 ) "
 Harness: the test ran to completion.
 

third_party/blink/web_tests/animations/custom-properties/custom-color-list-type-interpolation.html

@@ -66,10 +66,6 @@ assertInterpolation({
   {at: 1.5, is: 'rgb(0, 0, 192) rgb(0, 0, 255)'}
 ]);
 
-// Composition and neutralKeyframe tests assume that composite:add means
-// component-wise addition, which may or may not be the behavior we want.
-// https://github.com/w3c/css-houdini-drafts/issues/799
-
 assertInterpolation({
   property: '--color-list',
   from: neutralKeyframe,

third_party/blink/web_tests/animations/custom-properties/custom-integer-list-type-interpolation.html

@@ -90,10 +90,6 @@ assertInterpolation({
   {at: 1.45, is: '22 -7'}
 ]);
 
-// Composition and neutralKeyframe tests assume that composite:add means
-// component-wise addition, which may or may not be the behavior we want.
-// https://github.com/w3c/css-houdini-drafts/issues/799
-
 assertInterpolation({
   property: '--integer-list',
   from: neutralKeyframe,

third_party/blink/web_tests/animations/custom-properties/custom-length-list-type-interpolation.html

@@ -103,10 +103,6 @@ assertInterpolation({
   {at: 1.5, is: '145px'}
 ]);
 
-// Composition and neutralKeyframe tests assume that composite:add means
-// component-wise addition, which may or may not be the behavior we want.
-// https://github.com/w3c/css-houdini-drafts/issues/799
-
 assertInterpolation({
   property: '--length-list',
   from: neutralKeyframe,

third_party/blink/web_tests/animations/custom-properties/custom-length-percentage-list-type-interpolation.html

@@ -91,10 +91,6 @@ assertInterpolation({
   {at: 1.5, is: 'calc(150% + 150px)'}
 ]);
 
-// Composition and neutralKeyframe tests assume that composite:add means
-// component-wise addition, which may or may not be the behavior we want.
-// https://github.com/w3c/css-houdini-drafts/issues/799
-
 assertInterpolation({
   property: '--length-percentage-list',
   from: neutralKeyframe,

third_party/blink/web_tests/animations/custom-properties/custom-list-type-interpolation.html

@@ -86,10 +86,6 @@ assertNoInterpolation({
   to: '10px'
 });
 
-// Composition tests assume that composite:add mean component-wise addition,
-// which may or may not be the behavior we want.
-// https://github.com/w3c/css-houdini-drafts/issues/799
-
 // Verify that lists of different lengths don't interpolate:
 
 assertNoInterpolation({

third_party/blink/web_tests/animations/custom-properties/custom-number-list-type-interpolation.html

@@ -78,10 +78,6 @@ assertInterpolation({
   {at: 1.5, is: '145'}
 ]);
 
-// Composition and neutralKeyframe tests assume that composite:add means
-// component-wise addition, which may or may not be the behavior we want.
-// https://github.com/w3c/css-houdini-drafts/issues/799
-
 assertInterpolation({
   property: '--number-list',
   from: neutralKeyframe,

third_party/blink/web_tests/animations/custom-properties/custom-percentage-list-type-interpolation.html

@@ -78,10 +78,6 @@ assertInterpolation({
   {at: 1.5, is: '145%'}
 ]);
 
-// Composition and neutralKeyframe tests assume that composite:add means
-// component-wise addition, which may or may not be the behavior we want.
-// https://github.com/w3c/css-houdini-drafts/issues/799
-
 assertInterpolation({
   property: '--percentage-list',
   from: neutralKeyframe,

third_party/blink/web_tests/animations/custom-properties/custom-resolution-list-type-interpolation.html

@@ -90,10 +90,6 @@ assertInterpolation({
   {at: 1.5, is: '2.5dppx 2dppx'}
 ]);
 
-// Composition and neutralKeyframe tests assume that composite:add means
-// component-wise addition, which may or may not be the behavior we want.
-// https://github.com/w3c/css-houdini-drafts/issues/799
-
 assertInterpolation({
   property: '--resolution-list',
   from: neutralKeyframe,

third_party/blink/web_tests/animations/custom-properties/custom-time-list-type-interpolation.html

@@ -90,10 +90,6 @@ assertInterpolation({
   {at: 1.5, is: '1.5s -0.5s'}
 ]);
 
-// Composition and neutralKeyframe tests assume that composite:add means
-// component-wise addition, which may or may not be the behavior we want.
-// https://github.com/w3c/css-houdini-drafts/issues/799
-
 assertInterpolation({
   property: '--time-list',
   from: neutralKeyframe,