Remove cr.isGTK; it's not used any more.

ui/webui/resources/js/cr.js

 // Copyright (c) 2012 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.
 
 /**
  * The global object.
  * @type {!Object}
  * @const
  */
 var global = this;
@@ skipping 309 matching lines @@
      * Whether this is on chromeOS or not.
      */
     cr.isChromeOS = /CrOS/.test(navigator.userAgent);
 
     /**
      * Whether this is on vanilla Linux (not chromeOS).
      */
     cr.isLinux = /Linux/.test(navigator.userAgent);
 
     /**
-     * Whether this uses GTK or not.
-     */
-    cr.isGTK = typeof chrome.getVariableValue == 'function' &&
-        /GTK/.test(chrome.getVariableValue('toolkit'));
-
-    /**
      * Whether this uses the views toolkit or not.
      */
     cr.isViews = typeof chrome.getVariableValue == 'function' &&
         /views/.test(chrome.getVariableValue('toolkit'));
   }
 
   return {
     addSingletonGetter: addSingletonGetter,
     createUid: createUid,
     define: define,
     defineProperty: defineProperty,
     dispatchPropertyChange: dispatchPropertyChange,
     dispatchSimpleEvent: dispatchSimpleEvent,
     getUid: getUid,
     initialize: initialize,
     PropertyKind: PropertyKind
   };
 })();
 
 
 /**
  * TODO(kgr): Move this to another file which is to be loaded last.
  * This will be done as part of future work to make this code pre-compilable.
  */
 cr.initialize();