DevTools: Do not linkify to pseudo (program) node when there's no URL

third_party/WebKit/Source/devtools/front_end/sources/CallStackSidebarPane.js

 /*
  * Copyright (C) 2008 Apple 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 433 matching lines @@
  */
 WebInspector.CallStackSidebarPane.CallFrame = function(functionName, location, linkifier, debuggerCallFrame, locationPool, asyncCallFrame)
 {
     WebInspector.UIList.Item.call(this, WebInspector.beautifyFunctionName(functionName), "");
     this._location = location;
     this._debuggerCallFrame = debuggerCallFrame;
     this._asyncCallFrame = asyncCallFrame;
 
     if (asyncCallFrame) {
         var locationElement = linkifier.linkifyRawLocation(location, location.script().sourceURL);
-        this.subtitleElement.appendChild(locationElement);
+        if (locationElement)
+            this.subtitleElement.appendChild(locationElement);
     } else {
         this._liveLocationPool = new WebInspector.LiveLocationPool();
         WebInspector.debuggerWorkspaceBinding.createCallFrameLiveLocation(location, this._update.bind(this), locationPool);
     }
 }
 
 WebInspector.CallStackSidebarPane.CallFrame.prototype = {
     /**
      * @param {!WebInspector.LiveLocation} liveLocation
      */
     _update: function(liveLocation)
     {
         var uiLocation = liveLocation.uiLocation();
         if (!uiLocation)
             return;
         var text = uiLocation.linkText();
         this.setSubtitle(text.trimMiddle(30));
         this.subtitleElement.title = text;
     },
 
     __proto__: WebInspector.UIList.Item.prototype
 }