IDL: Support iterable<>, maplike<> and setlike<> syntax

Source/modules/webmidi/MIDIOutputMap.idl

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // FIXME: Implement forEach.
 // callback ForEachCallback = void(DOMString id, MIDIOutput port);
 
 [
-    Iterable,
     NoInterfaceObject,
     GarbageCollected,
 ] interface MIDIOutputMap {
     readonly attribute unsigned long size;
     Iterator keys();
     Iterator entries();
     Iterator values();
     // This function returns undefined if |!this->has(id)|.
     [ImplementedAs=getForBinding, CallWith=ScriptState] any get(DOMString id);
     boolean has(DOMString key);
     // FIXME: Implement forEach.
     // void forEach (ForEachCallback callback);
+    readonly maplike<DOMString, MIDIOutput>;
 };