Add use counters for lots of DOM APIs.

third_party/WebKit/Source/modules/broadcastchannel/BroadcastChannel.idl

 // Copyright 2016 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.
 
 // https://html.spec.whatwg.org/multipage/comms.html#broadcastchannel
 
 [
     Constructor(DOMString name),
     ConstructorCallWith=ExecutionContext,
     RaisesException=Constructor,
     RuntimeEnabled=BroadcastChannel,
     Exposed=(Window,Worker),
     ActiveScriptWrappable,
     DependentLifetime,
     Measure,
 ] interface BroadcastChannel : EventTarget {
-    readonly attribute DOMString name;
+    [Measure] readonly attribute DOMString name;
 
     [RaisesException, Measure] void postMessage(any message);
     [Measure] void close();
 
     // event handlers
-    attribute EventHandler onmessage;
+    [Measure] attribute EventHandler onmessage;
 };