Web Animations: Add CSSAnimatableValueFactory API (partial implementation)

Source/core/core.gypi

 {
     'variables': {
         'deprecated_perl_core_idl_files': [
             'css/CSS.idl',
             'css/CSSCharsetRule.idl',
             'css/CSSFontFaceLoadEvent.idl',
             'css/CSSFontFaceRule.idl',
             'css/CSSHostRule.idl',
             'css/CSSImportRule.idl',
             'css/CSSMediaRule.idl',
@@ skipping 3725 matching lines @@
         ],
         'core_unittest_files': [
             'animation/AnimatableNeutralTest.cpp',
             'animation/AnimatableNumberTest.cpp',
             'animation/AnimatableUnknownTest.cpp',
             'animation/DocumentTimelineTest.cpp',
             'animation/KeyframeAnimationEffectTest.cpp',
             'animation/PlayerTest.cpp',
             'animation/TimedItemCalculationsTest.cpp',
             'animation/TimedItemTest.cpp',
+            'animation/css/CSSAnimatableValueFactory.cpp',
+            'animation/css/CSSAnimatableValueFactory.h',
             'css/CSSParserValuesTest.cpp',
             'html/TimeRangesTest.cpp',
             'loader/cache/CachedImageTest.cpp',
             'loader/cache/MemoryCacheTest.cpp',
             'loader/cache/ResourceFetcherTest.cpp',
             'platform/DecimalTest.cpp',
             'platform/SharedBufferTest.cpp',
             'platform/chromium/ClipboardChromiumTest.cpp',
             'platform/graphics/FontTest.cpp',
             'platform/graphics/GraphicsContextTest.cpp',
@@ skipping 41 matching lines @@
                 'bison_exe': 'bison',
                 # We specify a preprocess so it happens locally and won't get
                 # distributed to goma.
                 # FIXME: /usr/bin/gcc won't exist on OSX forever. We want to
                 # use /usr/bin/clang once we require Xcode 4.x.
                 'preprocessor': '--preprocessor "/usr/bin/gcc -E -P -x c++"'
               }],
          ],
     }
 }