Use Promises for screen.lockOrientation().

Source/web/web.gypi

 {
   'variables': {
     'web_files': [
       'AssertMatchingEnums.cpp',
       'AssociatedURLLoader.cpp',
       'AssociatedURLLoader.h',
       'BackForwardClientImpl.cpp',
       'BackForwardClientImpl.h',
       'ChromeClientImpl.cpp',
       'ChromeClientImpl.h',
@@ skipping 101 matching lines @@
       'WebColorName.cpp',
       'WebColorSuggestion.cpp',
       'WebCustomElement.cpp',
       'WebDOMActivityLogger.cpp',
       'WebDOMCustomEvent.cpp',
       'WebDOMError.cpp',
       'WebDOMEvent.cpp',
       'WebDOMEventListener.cpp',
       'WebDOMEventListenerPrivate.cpp',
       'WebDOMEventListenerPrivate.h',
+      'WebDOMException.cpp',
       'WebDOMFileSystem.cpp',
       'WebDOMMediaStreamTrack.cpp',
       'WebDOMMessageEvent.cpp',
       'WebDOMMouseEvent.cpp',
       'WebDOMProgressEvent.cpp',
       'WebDOMResourceProgressEvent.cpp',
       'WebDateTimeSuggestion.cpp',
       'WebDataSourceImpl.cpp',
       'WebDataSourceImpl.h',
       'WebDatabase.cpp',
@@ skipping 204 matching lines @@
       ['os_posix==1 and OS!="mac"',
         {
           'web_unittest_files': [
             'tests/LocaleICUTest.cpp',
           ],
         }
       ],
     ],
   },
 }