Issue 450 - Create shadow root immediatelly instead inside the reponse callback

include.preload.js

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2014 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 var SELECTOR_GROUP_SIZE = 20;
 
+// use Shadow DOM if available to don't mess with web pages that
+// rely on the order of their own <style> tags. However
+// the <shadow> element is broken in some Chrome 32 builds (#309)
+//
+// also we must not create the shadow root in the response callback passed
+// to sendMessage(), otherwise Chrome breaks some websites (#450)
+var shadow = null;
+if ("webkitCreateShadowRoot" in document.documentElement && !/\bChrome\/32\b/.test(navigator.userAgent))
+{
+  shadow = document.documentElement.webkitCreateShadowRoot();
+  shadow.appendChild(document.createElement("shadow"));
+}
+
 // Sets the currently used CSS rules for elemhide filters
 function setElemhideCSSRules(selectors)
 {
   if (selectors.length == 0)
     return;
 
   var style = document.createElement("style");
   style.setAttribute("type", "text/css");
 
-  // Use Shadow DOM if available to don't mess with web pages that
-  // rely on the order of their own <style> tags. However
-  // the <shadow> element is broken in some Chrome 32 builts (#309)
-  if ("webkitCreateShadowRoot" in document.documentElement && !/\bChrome\/32\b/.test(navigator.userAgent))
+  if (shadow)
   {
-    var shadow = document.documentElement.webkitCreateShadowRoot();
-    shadow.appendChild(document.createElement("shadow"));
     shadow.appendChild(style);
 
     try
     {
       document.querySelector("::content");
 
       for (var i = 0; i < selectors.length; i++)
         selectors[i] = "::content " + selectors[i];
     }
     catch (e)
@@ skipping 76 matching lines @@
     ext.backgroundPage.sendMessage({type: "add-key-exception", token: attr});
 
   ext.backgroundPage.sendMessage({type: "get-selectors"}, setElemhideCSSRules);
 }
 
 // In Chrome 18 the document might not be initialized yet
 if (document.documentElement)
   init();
 else
   window.setTimeout(init, 0);