Fix behaviour of shadow interpolation with mismatched list lengths

third_party/WebKit/Source/core/animation/CSSShadowListInterpolationType.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/animation/CSSShadowListInterpolationType.h"
 
 #include <memory>
 #include "core/animation/ListInterpolationFunctions.h"
 #include "core/animation/ShadowInterpolationFunctions.h"
 #include "core/animation/ShadowListPropertyFunctions.h"
@@ skipping 98 matching lines @@
         return ShadowInterpolationFunctions::MaybeConvertCSSValue(
             value_list.Item(index));
       });
 }
 
 PairwiseInterpolationValue CSSShadowListInterpolationType::MaybeMergeSingles(
     InterpolationValue&& start,
     InterpolationValue&& end) const {
   return ListInterpolationFunctions::MaybeMergeSingles(
       std::move(start), std::move(end),
+      ListInterpolationFunctions::kPadToLargest,
       ShadowInterpolationFunctions::MaybeMergeSingles);
 }
 
 InterpolationValue
 CSSShadowListInterpolationType::MaybeConvertStandardPropertyUnderlyingValue(
     const ComputedStyle& style) const {
   return ConvertShadowList(
       ShadowListPropertyFunctions::GetShadowList(CssProperty(), style),
       style.EffectiveZoom());
 }
 
 void CSSShadowListInterpolationType::Composite(
     UnderlyingValueOwner& underlying_value_owner,
     double underlying_fraction,
     const InterpolationValue& value,
     double interpolation_fraction) const {
   ListInterpolationFunctions::Composite(
       underlying_value_owner, underlying_fraction, *this, value,
+      ListInterpolationFunctions::kPadToLargest,
       ShadowInterpolationFunctions::NonInterpolableValuesAreCompatible,
       ShadowInterpolationFunctions::Composite);
 }
 
 static PassRefPtr<ShadowList> CreateShadowList(
     const InterpolableValue& interpolable_value,
     const NonInterpolableValue* non_interpolable_value,
     const StyleResolverState& state) {
   const InterpolableList& interpolable_list =
       ToInterpolableList(interpolable_value);
@@ skipping 12 matching lines @@
 void CSSShadowListInterpolationType::ApplyStandardPropertyValue(
     const InterpolableValue& interpolable_value,
     const NonInterpolableValue* non_interpolable_value,
     StyleResolverState& state) const {
   ShadowListPropertyFunctions::SetShadowList(
       CssProperty(), *state.Style(),
       CreateShadowList(interpolable_value, non_interpolable_value, state));
 }
 
 }  // namespace blink