DevTools: Get rid of synchronous XHRs in the frontend code

Source/devtools/front_end/sources/StyleSheetOutlineDialog.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:
  *
  * 1. Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *
@@ skipping 19 matching lines @@
  * @constructor
  * @extends {WebInspector.SelectionDialogContentProvider}
  * @param {!WebInspector.UISourceCode} uiSourceCode
  * @param {function(number, number)} selectItemCallback
  */
 WebInspector.StyleSheetOutlineDialog = function(uiSourceCode, selectItemCallback)
 {
     WebInspector.SelectionDialogContentProvider.call(this);
     this._selectItemCallback = selectItemCallback;
     this._cssParser = new WebInspector.CSSParser();
-    this._cssParser.addEventListener(WebInspector.CSSParser.Events.RulesParsed, this.refresh.bind(this));
-    this._cssParser.parse(uiSourceCode.workingCopy());
+    this._cssParser.parse(uiSourceCode.workingCopy()).then(this.refresh.bind(this));
 }
 
 /**
  * @param {!WebInspector.View} view
  * @param {!WebInspector.UISourceCode} uiSourceCode
  * @param {function(number, number)} selectItemCallback
  */
 WebInspector.StyleSheetOutlineDialog.show = function(view, uiSourceCode, selectItemCallback)
 {
     if (WebInspector.Dialog.currentInstance())
@@ skipping 59 matching lines @@
             this._selectItemCallback(lineNumber, rule.columnNumber);
     },
 
     dispose: function()
     {
         this._cssParser.dispose();
     },
 
     __proto__: WebInspector.SelectionDialogContentProvider.prototype
 }