Add a native subtype of function that uses the native C++ class hierarchy to check if an element

Source/bindings/dart/gyp/overrides.gypi

 {
   'variables': {
     'additional_target_deps': [
       '../bindings/dart/gyp/dartium.gyp:dart_debug_hooks_source',
       '../bindings/dart/gyp/dartium.gyp:dart_snapshot#host',
       '../../../../dart/runtime/dart-runtime.gyp:libdart',
     ],
     'additional_webcore_include_dirs': [
       '..',
       '../custom',
@@ skipping 178 matching lines @@
         '../custom/DartWebGLRenderingContextCustom.cpp',
         '../custom/DartWebKitPointCustom.cpp',
         '../custom/DartWebSocketCustom.cpp',
         '../custom/DartWindowCustom.cpp',
         '../custom/DartWorkerCryptoCustom.cpp',
         '../custom/DartWorkerCustom.cpp',
         '../custom/DartWorkerGlobalScopeCustom.cpp',
         '../custom/DartXMLHttpRequestCustom.cpp',
         '../custom/DartXSLTProcessorCustom.cpp',
         '<(SHARED_INTERMEDIATE_DIR)/blink/DartHTMLElementWrapperFactory.cpp',
+        '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/DartWebkitClassIds.cpp',
         '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/html_DartResolver.cpp',
         '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/indexed_db_DartResolver.cpp',
         '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/svg_DartResolver.cpp',
         '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/web_audio_DartResolver.cpp',
         '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/web_gl_DartResolver.cpp',
         '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/web_sql_DartResolver.cpp',
         '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/DartSnapshot.bytes',
         # FIXME: make conditional.
         '<(SHARED_INTERMEDIATE_DIR)/blink/DartSVGElementWrapperFactory.cpp',
     ],
@@ skipping 23 matching lines @@
           '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/DartDerivedSources16.cpp',
           '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/DartDerivedSources17.cpp',
           '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/DartDerivedSources18.cpp',
           '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/DartDerivedSources19.cpp',
           '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/dart/DartDerivedSources20.cpp',
         ],
       }],
     ],
   },
 }