DevTools: make flame chart a web component.

Source/devtools/front_end/main/HelpScreenUntilReload.js

 /*
  * Copyright (C) 2013 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 19 matching lines @@
 
 /**
  * @constructor
  * @param {string=} title
  * @param {string=} message
  * @extends {WebInspector.HelpScreen}
  */
 WebInspector.HelpScreenUntilReload = function(title, message)
 {
     WebInspector.HelpScreen.call(this, title);
-    var p = this.contentElement.createChild("p");
+    var p = this.helpContentElement.createChild("p");
     p.classList.add("help-section");
     p.textContent = message;
     WebInspector.debuggerModel.addEventListener(WebInspector.DebuggerModel.Events.GlobalObjectCleared, this.hide, this);
 }
 
 WebInspector.HelpScreenUntilReload.prototype = {
     /**
      * @override
      */
     willHide: function()
     {
         WebInspector.debuggerModel.removeEventListener(WebInspector.DebuggerModel.Events.GlobalObjectCleared, this.hide, this);
         WebInspector.HelpScreen.prototype.willHide.call(this);
     },
 
     __proto__: WebInspector.HelpScreen.prototype
 }