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

third_party/WebKit/Source/devtools/front_end/sdk/ConsoleModel.js

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 31 matching lines @@
     /** @type {!Map<number, !WebInspector.ConsoleMessage>} */
     this._messageByExceptionId = new Map();
     this._warnings = 0;
     this._errors = 0;
     this._revokedErrors = 0;
     this._logAgent = target.logAgent();
     target.registerLogDispatcher(new WebInspector.LogDispatcher(this));
     this._logAgent.enable();
 }
 
+/** @enum {string} */
 WebInspector.ConsoleModel.Events = {
     ConsoleCleared: "ConsoleCleared",
     MessageAdded: "MessageAdded",
     MessageUpdated: "MessageUpdated",
-    CommandEvaluated: "CommandEvaluated",
+    CommandEvaluated: "CommandEvaluated"
 }
 
 WebInspector.ConsoleModel.prototype = {
     /**
      * @param {!WebInspector.ConsoleMessage} msg
      */
     addMessage: function(msg)
     {
         if (this._isBlacklisted(msg))
             return;
@@ skipping 589 matching lines @@
         this.dispatchEventToListeners(WebInspector.ConsoleModel.Events.CommandEvaluated, event.data);
     },
 
     __proto__: WebInspector.Object.prototype
 }
 
 /**
  * @type {!WebInspector.MultitargetConsoleModel}
  */
 WebInspector.multitargetConsoleModel;