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

third_party/WebKit/Source/devtools/front_end/bindings/ResourceScriptMapping.js

 /*
  * Copyright (C) 2012 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 278 matching lines @@
     this._uiSourceCode = uiSourceCode;
     this._uiSourceCode.forceLoadOnCheckContent();
 
     if (this._uiSourceCode.contentType().isScript())
         this._script = scripts[0];
 
     this._uiSourceCode.addEventListener(WebInspector.UISourceCode.Events.WorkingCopyChanged, this._workingCopyChanged, this);
     this._uiSourceCode.addEventListener(WebInspector.UISourceCode.Events.WorkingCopyCommitted, this._workingCopyCommitted, this);
 }
 
+/** @enum {symbol} */
 WebInspector.ResourceScriptFile.Events = {
-    DidMergeToVM: "DidMergeToVM",
-    DidDivergeFromVM: "DidDivergeFromVM",
+    DidMergeToVM: Symbol("DidMergeToVM"),
+    DidDivergeFromVM: Symbol("DidDivergeFromVM"),
 }
 
 WebInspector.ResourceScriptFile.prototype = {
     /**
      * @param {!Array.<!WebInspector.Script>} scripts
      * @return {boolean}
      */
     _hasScripts: function(scripts)
     {
         return this._script && this._script === scripts[0];
@@ skipping 169 matching lines @@
     /**
      * @return {boolean}
      */
     hasSourceMapURL: function()
     {
         return this._script && !!this._script.sourceMapURL;
     },
 
     __proto__: WebInspector.Object.prototype
 }