Use "Dictionary" for PositionOptions instead of Custom binding

Source/modules/modules.gypi

 {
   'includes': [
     '../core/core_generated.gypi',
     'modules_generated.gypi',
   ],
   'variables': {
     # Experimental hooks for embedder to provide extra IDL and source files.
     #
     # Note: this is not a supported API. If you rely on this, you will be broken
     # from time to time as the code generator changes in backward incompatible
@@ skipping 439 matching lines @@
       'gamepad/WebKitGamepad.cpp',
       'gamepad/WebKitGamepad.h',
       'gamepad/WebKitGamepadList.cpp',
       'gamepad/WebKitGamepadList.h',
       'geolocation/Coordinates.cpp',
       'geolocation/Geolocation.cpp',
       'geolocation/GeolocationController.cpp',
       'geolocation/GeolocationInspectorAgent.cpp',
       'geolocation/NavigatorGeolocation.cpp',
       'geolocation/NavigatorGeolocation.h',
+      'geolocation/PositionOptions.cpp',
+      'geolocation/PositionOptions.h',
       'imagebitmap/ImageBitmapFactories.cpp',
       'imagebitmap/ImageBitmapFactories.h',
       'indexeddb/DOMWindowIndexedDatabase.cpp',
       'indexeddb/DOMWindowIndexedDatabase.h',
       'indexeddb/IDBAny.cpp',
       'indexeddb/IDBAny.h',
       'indexeddb/IDBCursor.cpp',
       'indexeddb/IDBCursor.h',
       'indexeddb/IDBCursorWithValue.cpp',
       'indexeddb/IDBCursorWithValue.h',
@@ skipping 506 matching lines @@
       'indexeddb/IDBRequestTest.cpp',
       'indexeddb/IDBTransactionTest.cpp',
       'websockets/WebSocketDeflaterTest.cpp',
       'websockets/WebSocketExtensionDispatcherTest.cpp',
       'websockets/WebSocketExtensionParserTest.cpp',
       'websockets/WebSocketPerMessageDeflateTest.cpp',
       'websockets/WebSocketTest.cpp',
     ],
   },
 }