Remove meaningless uses of [TypeChecking=Nullable]

Source/modules/imagebitmap/ImageBitmapFactories.idl

 /*
  * Copyright (c) 2013, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 28 matching lines @@
          Blob or
          ImageData or
          // CanvasRenderingContext2D or
          ImageBitmap) ImageBitmapSource;
 */
 
 [
     LegacyTreatAsPartialInterface,
     NoInterfaceObject, // Always used on target of 'implements'
     RuntimeEnabled=ExperimentalCanvasFeatures,
-    TypeChecking=Interface|Nullable,
+    TypeChecking=Interface,
 ] interface ImageBitmapFactories {
     [CallWith=ScriptState, RaisesException] Promise createImageBitmap(Blob blob);
     [CallWith=ScriptState, RaisesException] Promise createImageBitmap(Blob blob, long sx, long sy, long sw, long sh);
     [CallWith=ScriptState, RaisesException] Promise createImageBitmap(ImageData data);
     [CallWith=ScriptState, RaisesException] Promise createImageBitmap(ImageData data, long sx, long sy, long sw, long sh);
     [CallWith=ScriptState, RaisesException] Promise createImageBitmap(ImageBitmap bitmap);
     [CallWith=ScriptState, RaisesException] Promise createImageBitmap(ImageBitmap bitmap, long sx, long sy, long sw, long sh);
 };
 
 Window implements ImageBitmapFactories;
 WorkerGlobalScope implements ImageBitmapFactories;