Remove InbandTextTrackPrivate/InbandTextTrackPrivateClient

Source/web/web.gypi

 {
   'variables': {
     'web_files': [
       'ApplicationCacheHost.cpp',
       'ApplicationCacheHostInternal.h',
       'AssertMatchingEnums.cpp',
       'AssociatedURLLoader.cpp',
       'AssociatedURLLoader.h',
       'AutofillPopupMenuClient.cpp',
       'AutofillPopupMenuClient.h',
@@ skipping 36 matching lines @@
       'GeolocationClientProxy.cpp',
       'GeolocationClientProxy.h',
       'GraphicsLayerFactoryChromium.cpp',
       'GraphicsLayerFactoryChromium.h',
       'IDBCursorBackendProxy.cpp',
       'IDBCursorBackendProxy.h',
       'IDBDatabaseBackendProxy.cpp',
       'IDBDatabaseBackendProxy.h',
       'IDBFactoryBackendProxy.cpp',
       'IDBFactoryBackendProxy.h',
-      'InbandTextTrackPrivateImpl.cpp',
-      'InbandTextTrackPrivateImpl.h',
       'InspectorClientImpl.cpp',
       'InspectorClientImpl.h',
       'InspectorFrontendClientImpl.cpp',
       'InspectorFrontendClientImpl.h',
       'LinkHighlight.cpp',
       'LinkHighlight.h',
       'LocalFileSystemClient.cpp',
       'LocalFileSystemClient.h',
       'MIDIClientProxy.cpp',
       'MIDIClientProxy.h',
@@ skipping 296 matching lines @@
         {
           'web_unittest_files': [
             'tests/KeyCodeConversionTestGtk.cpp',
             'tests/WebInputEventFactoryTestGtk.cpp',
           ],
         }
       ],
     ],
   },
 }