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

third_party/WebKit/Source/devtools/front_end/sources/SourcesView.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
  * @implements {WebInspector.TabbedEditorContainerDelegate}
  * @implements {WebInspector.Searchable}
  * @implements {WebInspector.Replaceable}
  * @extends {WebInspector.VBox}
@@ skipping 59 matching lines @@
         for (var i = 0; i < unsavedSourceCodes.length; ++i)
             WebInspector.Revealer.reveal(unsavedSourceCodes[i]);
     }
     if (!window.opener)
         window.addEventListener("beforeunload", handleBeforeUnload, true);
 
     this._shortcuts = {};
     this.element.addEventListener("keydown", this._handleKeyDown.bind(this), false);
 }
 
+/** @enum {symbol} */
 WebInspector.SourcesView.Events = {
-    EditorClosed: "EditorClosed",
-    EditorSelected: "EditorSelected",
+    EditorClosed: Symbol("EditorClosed"),
+    EditorSelected: Symbol("EditorSelected"),
 }
 
 WebInspector.SourcesView.prototype = {
     /**
      * @param {function(!Array.<!WebInspector.KeyboardShortcut.Descriptor>, function(!Event=):boolean)} registerShortcutDelegate
      */
     registerShortcuts: function(registerShortcutDelegate)
     {
         /**
          * @this {WebInspector.SourcesView}
@@ skipping 682 matching lines @@
      */
     handleAction: function(context, actionId)
     {
         var sourcesView = WebInspector.context.flavor(WebInspector.SourcesView);
         if (!sourcesView)
             return false;
         sourcesView._editorContainer.closeAllFiles();
         return true;
     }
 }