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

third_party/WebKit/Source/devtools/front_end/workspace/UISourceCode.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 44 matching lines @@
     this._lineDecorations = new Map();
 
     /** @type {!Array.<!WebInspector.Revision>} */
     this.history = [];
     this._hasUnsavedCommittedChanges = false;
 
     /** @type {!Array<!WebInspector.UISourceCode.Message>} */
     this._messages = [];
 }
 
-/**
- * @enum {string}
- */
+/** @enum {symbol} */
 WebInspector.UISourceCode.Events = {
-    WorkingCopyChanged: "WorkingCopyChanged",
-    WorkingCopyCommitted: "WorkingCopyCommitted",
-    TitleChanged: "TitleChanged",
-    SourceMappingChanged: "SourceMappingChanged",
-    MessageAdded: "MessageAdded",
-    MessageRemoved: "MessageRemoved",
-    LineDecorationAdded: "LineDecorationAdded",
-    LineDecorationRemoved: "LineDecorationRemoved"
+    WorkingCopyChanged: Symbol("WorkingCopyChanged"),
+    WorkingCopyCommitted: Symbol("WorkingCopyCommitted"),
+    TitleChanged: Symbol("TitleChanged"),
+    SourceMappingChanged: Symbol("SourceMappingChanged"),
+    MessageAdded: Symbol("MessageAdded"),
+    MessageRemoved: Symbol("MessageRemoved"),
+    LineDecorationAdded: Symbol("LineDecorationAdded"),
+    LineDecorationRemoved: Symbol("LineDecorationRemoved")
 }
 
 WebInspector.UISourceCode.prototype = {
     /**
      * @return {string}
      */
     name: function()
     {
         return this._name;
     },
@@ skipping 887 matching lines @@
     },
 
     /**
      * @return {*}
      */
     data: function()
     {
         return this._data;
     }
 }