Refactoring: Extract DocumentInit for capture Document construction parameter.

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 1768 matching lines @@
             'dom/DeviceOrientationController.h',
             'dom/DeviceOrientationData.cpp',
             'dom/DeviceOrientationEvent.cpp',
             'dom/DeviceOrientationEvent.h',
             'dom/Document.cpp',
             'dom/DocumentEventQueue.cpp',
             'dom/DocumentEventQueue.h',
             'dom/DocumentFragment.cpp',
             'dom/DocumentFullscreen.cpp',
             'dom/DocumentFullscreen.h',
+            'dom/DocumentInitializer.cpp',
+            'dom/DocumentInitializer.h',
             'dom/DocumentLifecycleObserver.cpp',
             'dom/DocumentLifecycleObserver.h',
             'dom/DocumentMarkerController.cpp',
             'dom/DocumentMarker.cpp',
             'dom/DocumentOrderedList.cpp',
             'dom/DocumentOrderedList.h',
             'dom/DocumentOrderedMap.cpp',
             'dom/DocumentParser.cpp',
             'dom/DocumentSharedObjectPool.cpp',
             'dom/DocumentStyleSheetCollection.cpp',
@@ skipping 1992 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++"'
               }],
          ],
     }
 }