Implement initial part of WebEmbeddedWorker

Source/web/web.gypi

 {
   'variables': {
     'web_files': [
       'ApplicationCacheHost.cpp',
       'ApplicationCacheHostInternal.h',
       'AssertMatchingEnums.cpp',
       'AssociatedURLLoader.cpp',
       'AssociatedURLLoader.h',
       'AutofillPopupMenuClient.cpp',
       'AutofillPopupMenuClient.h',
@@ skipping 118 matching lines @@
       'WebDataSourceImpl.h',
       'WebDatabase.cpp',
       'WebDevToolsAgentImpl.cpp',
       'WebDevToolsAgentImpl.h',
       'WebDevToolsFrontendImpl.cpp',
       'WebDevToolsFrontendImpl.h',
       'WebDocument.cpp',
       'WebDocumentType.cpp',
       'WebDragData.cpp',
       'WebElement.cpp',
+      'WebEmbeddedWorkerImpl.cpp',
+      'WebEmbeddedWorkerImpl.h',
       'WebEntities.cpp',
       'WebEntities.h',
       'WebFileChooserCompletionImpl.cpp',
       'WebFileChooserCompletionImpl.h',
       'WebFontCache.cpp',
       'WebFontDescription.cpp',
       'WebFontImpl.cpp',
       'WebFontImpl.h',
       'WebFormControlElement.cpp',
       'WebFormElement.cpp',
@@ skipping 205 matching lines @@
         {
           'web_unittest_files': [
             'tests/KeyCodeConversionTestGtk.cpp',
             'tests/WebInputEventFactoryTestGtk.cpp',
           ],
         }
       ],
     ],
   },
 }