Upgrade elements that are created before a custom element definition is registered

Source/core/core.gypi

 {
     'variables': {
         'core_idl_files': [
             'css/CSSCharsetRule.idl',
             'css/CSSFontFaceLoadEvent.idl',
             'css/CSSFontFaceRule.idl',
             'css/CSSHostRule.idl',
             'css/CSSImportRule.idl',
             'css/CSSMediaRule.idl',
             'css/CSSPageRule.idl',
@@ skipping 1677 matching lines @@
             'dom/ContextDestructionObserver.cpp',
             'dom/ContextFeatures.cpp',
             'dom/ContextFeatures.h',
             'dom/CrossThreadTask.h',
             'dom/CustomElementConstructor.cpp',
             'dom/CustomElementConstructor.h',
             'dom/CustomElementDefinition.cpp',
             'dom/CustomElementDefinition.h',
             'dom/CustomElementRegistry.cpp',
             'dom/CustomElementRegistry.h',
+            'dom/CustomElementUpgradeCandidateMap.cpp',
+            'dom/CustomElementUpgradeCandidateMap.h',
             'dom/CustomEvent.cpp',
             'dom/CustomEvent.h',
             'dom/DOMCoreException.cpp',
             'dom/DOMCoreException.h',
             'dom/DOMError.cpp',
             'dom/DOMError.h',
             'dom/DOMImplementation.cpp',
             'dom/DOMNamedFlowCollection.cpp',
             'dom/DOMNamedFlowCollection.h',
             'dom/DOMStringList.cpp',
@@ skipping 1976 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++"'
               }],
          ],
     }
 }