Fix issue with comments and thumbnails not loading on YouTube in Safari

safari/include.youtube.js

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@@ skipping 51 matching lines @@
     if (flashvarsChanged)
       player.parentNode.replaceChild(newPlayer, player);
 
     // if history.pushState is available, YouTube uses the history API
     // when navigation from one video to another, and tells the flash
     // player with JavaScript which video and which ads to show next,
     // bypassing our flashvars rewrite code. So we disable
     // history.pushState on pages with YouTube's flash player.
     var script = document.createElement("script");
     script.type = "application/javascript";
-    script.id = "__disablePushState";
-    script.textContent = "history.pushState = undefined;" +
-                         "document.documentElement.removeChild(document.getElementById('__disablePushState'));";

[Sebastian Noack, 2014/02/28 21:54:22]

In the previous review Wladimir suggested that we should remove the script tag
from the DOM when it's not needed anymore:
http://codereview.adblockplus.org/4663448277352448/diff/5741031244955648/safa...

But Safari neither supports the onafterscriptexecuted event nor
window.currentScript. So the only way is to give the tag an ID. A randomized ID
might be preferable, but considering  that this is only on YouTube and that the
script tag is removed immediately, I preferred a hard-coded ID in favor of less
code.

[Wladimir Palant, 2014/03/03 07:21:13]

Why have the script remove itself? Using |script.async = false| instead and
removing the tag immediately after inserting it should work as well.

[Sebastian Noack, 2014/03/05 11:24:01]

Done.

+    script.async = false;
+    script.textContent = "history.pushState = undefined;";
     document.documentElement.appendChild(script);
+    document.documentElement.removeChild(script);
   }
 
   var deferred = [];
   function patchPlayerDeferred(player)
   {
     deferred.push(player);
   }
 
   var onBeforeLoadYoutubeVideo = patchPlayerDeferred;
   function onBeforeLoad(event)
   {
     if ((event.target.localName == "object" || event.target.localName == "embed") && /:\/\/[^\/]*\.ytimg\.com\//.test(event.url))
       onBeforeLoadYoutubeVideo(event.target);
   }
 
   ext.backgroundPage.sendMessage({type: "get-domain-enabled-state"}, function(response)
   {
     if (response.enabled)
     {
       deferred.forEach(patchPlayer);
       onBeforeLoadYoutubeVideo = patchPlayer;
     }
     else
       document.removeEventListener("beforeload", onBeforeLoad);
   });
 
   document.addEventListener("beforeload", onBeforeLoad, true);
 })();