[Bindings] Make maplike<> and setlike<> imply a readonly size attribute.

third_party/WebKit/Source/core/css/FontFaceSet.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 21 matching lines @@
 
 enum FontFaceSetLoadStatus { "loading", "loaded" };
 
 // TODO(foolip): This interface should be [Exposed=Window,Worker] and should
 // have a constructor, and thus not have [NoInterfaceObject].
 [
     DependentLifetime,
     NoInterfaceObject,
 ] interface FontFaceSet : EventTarget {
     setlike<FontFace>;
-    readonly attribute unsigned long size;
 
     // events for when loading state changes
     attribute EventHandler onloading;
     attribute EventHandler onloadingdone;
     attribute EventHandler onloadingerror;
 
     // check and start loads if appropriate
     // and fulfill promise when all loads complete
     [CallWith=ScriptState] Promise<sequence<FontFace>> load(DOMString font, optional DOMString text = " ");
 
     // return whether all fonts in the fontlist are loaded
     // (does not initiate load if not available)
     [RaisesException] boolean check(DOMString font, optional DOMString text = " ");
 
     // async notification that font loading and layout operations are done
     [CallWith=ScriptState] readonly attribute Promise<FontFaceSet> ready;
 
     // loading state, "loading" while one or more fonts loading, "loaded" otherwise
     readonly attribute FontFaceSetLoadStatus status;
 };