Add additive animation support for CSS properties perspective-origin and object-position

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/EffectModel.idl',
             'animation/AnimationEffectReadOnly.idl',
@@ skipping 861 matching lines @@
             'animation/CSSNumberInterpolationType.cpp',
             'animation/CSSNumberInterpolationType.h',
             'animation/CSSMotionRotationInterpolationType.cpp',
             'animation/CSSMotionRotationInterpolationType.h',
             'animation/CSSPaintInterpolationType.cpp',
             'animation/CSSPaintInterpolationType.h',
             'animation/CSSPathInterpolationType.cpp',
             'animation/CSSPathInterpolationType.h',
             'animation/CSSPositionAxisListInterpolationType.cpp',
             'animation/CSSPositionAxisListInterpolationType.h',
+            'animation/CSSPositionInterpolationType.h',
             'animation/CSSShadowListInterpolationType.cpp',
             'animation/CSSShadowListInterpolationType.h',
             'animation/CSSValueInterpolationType.cpp',
             'animation/CSSValueInterpolationType.h',
             'animation/CSSVisibilityInterpolationType.cpp',
             'animation/CSSVisibilityInterpolationType.h',
             'animation/CompositorAnimations.cpp',
             'animation/CompositorAnimations.h',
             'animation/CompositorAnimationsImpl.h',
             'animation/CompositorPendingAnimations.cpp',
@@ skipping 3138 matching lines @@
             'style/SVGComputedStyleTest.cpp',
             'svg/SVGPathParserTest.cpp',
             'svg/UnsafeSVGAttributeSanitizationTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }