Add two UseCounters for form.imageName and form.elements.imageName.

third_party/WebKit/Source/core/html/HTMLFormControlsCollection.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Samsung Electronics. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 184 matching lines @@
 
 void HTMLFormControlsCollection::namedGetter(const AtomicString& name, RadioNodeListOrElement& returnValue)
 {
     WillBeHeapVector<RefPtrWillBeMember<Element>> namedItems;
     this->namedItems(name, namedItems);
 
     if (namedItems.isEmpty())
         return;
 
     if (namedItems.size() == 1) {
+        if (isHTMLImageElement(*namedItems[0]))
+            UseCounter::count(document(), UseCounter::FormControlsCollectionNameAccessForImageElement);
         returnValue.setElement(namedItems.at(0));
         return;
     }
 
+    // This path never returns a RadioNodeList for <img> because
+    // onlyMatchingImgElements flag is false by default.
     returnValue.setRadioNodeList(ownerNode().radioNodeList(name));
 }
 
 void HTMLFormControlsCollection::supportedPropertyNames(Vector<String>& names)
 {
     // http://www.whatwg.org/specs/web-apps/current-work/multipage/common-dom-interfaces.html#htmlformcontrolscollection-0:
     // The supported property names consist of the non-empty values of all the id and name attributes
     // of all the elements represented by the collection, in tree order, ignoring later duplicates,
     // with the id of an element preceding its name if it contributes both, they differ from each
     // other, and neither is the duplicate of an earlier entry.
@@ skipping 17 matching lines @@
     }
 }
 
 DEFINE_TRACE(HTMLFormControlsCollection)
 {
     visitor->trace(m_cachedElement);
     HTMLCollection::trace(visitor);
 }
 
 }