DevTools: Use JS symbols instead of strings for eligible events.

third_party/WebKit/Source/devtools/front_end/timeline/TransformController.js

 /*
  * 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.
  */
 
 /**
  * @constructor
  * @extends {WebInspector.Object}
  * @param {!Element} element
@@ skipping 29 matching lines @@
     }
     this._setMode(WebInspector.TransformController.Modes.Pan);
 
     var resetButton = new WebInspector.ToolbarButton(WebInspector.UIString("Reset transform (0)"), "center-toolbar-item");
     resetButton.addEventListener("click", this.resetAndNotify.bind(this, undefined));
     this._controlPanelToolbar.appendToolbarItem(resetButton);
 
     this._reset();
 }
 
-/**
- * @enum {string}
- */
+/** @enum {symbol} */
 WebInspector.TransformController.Events = {
-    TransformChanged: "TransformChanged"
+    TransformChanged: Symbol("TransformChanged")
 }
 
 /**
  * @enum {string}
  */
 WebInspector.TransformController.Modes = {
     Pan: "Pan",
     Rotate: "Rotate",
 }
 
@@ skipping 261 matching lines @@
     _onDragEnd: function()
     {
         delete this._originX;
         delete this._originY;
         delete this._oldRotateX;
         delete this._oldRotateY;
     },
 
     __proto__: WebInspector.Object.prototype
 }