Revert of Upon load failure, remove sync script from execution queue.

Revert of Upon load failure, remove sync script from execution queue. (patchset #3 id:40001 of https://codereview.chromium.org/1263743002/)

Reason for revert:
Speculatively reverting to see if it addresses the recent crashes being reported via http://crbug.com/515419

Original issue's description:
> Upon load failure, remove sync script from execution queue.
> 
> If a script element is to be loaded synchronously and executed in order,
> it's queued for execution before loading. Should that load fail, the
> immediate execution of the script,
> 
>   https://html.spec.whatwg.org/#execute-the-script-block
> 
> should only result in an error event being dispatched.
> 
> Implementation-wise, along with signalling error, the failed script must also
> be removed from the internal in-order execution queue. We're done with
> (not) executing the script and failure to remove it will cause subsequent
> processing of the script execution queue to see the script as having failed
> to load and re-dispatch an error event.
> 
> R=haraken
> BUG=503077
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=199656

TBR=haraken@chromium.org,tkent@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=503077
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=199788

[sof, 2015-07-31 05:31:16]

Created Revert of Upon load failure, remove sync script from execution queue.

[commit-bot: I haz the power, 2015-07-31 05:31:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1271443002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1271443002/1

[commit-bot: I haz the power, 2015-07-31 05:32:09]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=199788

[haraken, 2015-07-31 06:10:28]

LGTM