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 726 matching lines @@
             'css/StyleRule.cpp',
             'css/StyleRule.h',
             'css/StyleRuleImport.cpp',
             'css/StyleRuleImport.h',
             'css/StyleSheet.cpp',
             'css/StyleSheet.h',
             'css/StyleSheetContents.cpp',
             'css/StyleSheetContents.h',
             'css/StyleSheetList.cpp',
             'css/StyleSheetList.h',
+            'css/resolver/CSSAnimatableValueFactory.cpp',
+            'css/resolver/CSSAnimatableValueFactory.h',
             'css/resolver/ElementStyleResources.cpp',
             'css/resolver/ElementStyleResources.h',
             'css/resolver/FilterOperationResolver.cpp',
             'css/resolver/FilterOperationResolver.h',
             'css/resolver/FontBuilder.cpp',
             'css/resolver/FontBuilder.h',
             'css/resolver/MatchedPropertiesCache.cpp',
             'css/resolver/MatchedPropertiesCache.h',
             'css/resolver/MatchResult.cpp',
             'css/resolver/MatchResult.h',
@@ skipping 3019 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++"'
               }],
          ],
     }
 }