Allow interpolation of background-size values with keywords in CSS Animations

third_party/WebKit/Source/core/core.gypi

 {
     'includes': [
         'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/KeyframeEffect.idl',
             'animation/AnimationEffectReadOnly.idl',
             'animation/AnimationEffectTiming.idl',
@@ skipping 933 matching lines @@
             'animation/CSSPathInterpolationType.h',
             'animation/CSSPositionAxisListInterpolationType.cpp',
             'animation/CSSPositionAxisListInterpolationType.h',
             'animation/CSSPositionInterpolationType.h',
             'animation/CSSRotateInterpolationType.cpp',
             'animation/CSSRotateInterpolationType.h',
             'animation/CSSScaleInterpolationType.cpp',
             'animation/CSSScaleInterpolationType.h',
             'animation/CSSShadowListInterpolationType.cpp',
             'animation/CSSShadowListInterpolationType.h',
+            'animation/CSSSizeListInterpolationType.cpp',
             'animation/CSSSizeListInterpolationType.h',
             'animation/CSSTextIndentInterpolationType.cpp',
             'animation/CSSTextIndentInterpolationType.h',
             'animation/CSSTransformOriginInterpolationType.h',
             'animation/CSSTransformInterpolationType.cpp',
             'animation/CSSTransformInterpolationType.h',
             'animation/CSSTranslateInterpolationType.cpp',
             'animation/CSSTranslateInterpolationType.h',
             'animation/CSSValueInterpolationType.cpp',
             'animation/CSSValueInterpolationType.h',
@@ skipping 55 matching lines @@
             'animation/PaintPropertyFunctions.cpp',
             'animation/PaintPropertyFunctions.h',
             'animation/PairwiseInterpolationValue.h',
             'animation/PathInterpolationFunctions.cpp',
             'animation/PathInterpolationFunctions.h',
             'animation/PrimitiveInterpolation.h',
             'animation/PropertyHandle.cpp',
             'animation/PropertyHandle.h',
             'animation/PropertyInterpolationTypesMapping.cpp',
             'animation/PropertyInterpolationTypesMapping.h',
+            'animation/SizeListPropertyFunctions.cpp',
+            'animation/SizeListPropertyFunctions.h',
             'animation/SVGAngleInterpolationType.cpp',
             'animation/SVGAngleInterpolationType.h',
             'animation/SVGIntegerInterpolationType.cpp',
             'animation/SVGIntegerInterpolationType.h',
             'animation/SVGIntegerOptionalIntegerInterpolationType.cpp',
             'animation/SVGIntegerOptionalIntegerInterpolationType.h',
             'animation/SVGInterpolationType.cpp',
             'animation/SVGInterpolationType.h',
             'animation/SVGLengthInterpolationType.cpp',
             'animation/SVGLengthInterpolationType.h',
@@ skipping 3255 matching lines @@
             'timing/MemoryInfoTest.cpp',
             'timing/PerformanceBaseTest.cpp',
             'timing/PerformanceObserverTest.cpp',
             'workers/DedicatedWorkerTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'workers/WorkerThreadTestHelper.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }