Revert of Hook up gin platform to blink, and explicitly manage the main thread isolate

Revert of Hook up gin platform to blink, and explicitly manage the main thread isolate (https://codereview.chromium.org/227653002/)

Reason for revert:
Broke browser_tests on Linux: http://build.chromium.org/p/chromium.webkit/builders/Linux%20Tests/builds/35802


Original issue's description:
> Hook up gin platform to blink, and explicitly manage the main thread isolate
> 
> We'll soon get rid of the v8 default isolate, so we'll need to manage
> our own.
> 
> To test the platform implementation, run with
>   --js-flags="--noparallel_sweeping --concurrent-sweeping --job-based-sweeping"
> 
> BUG=359977
> R=dcarney@chromium.org,haraken@chromium.org
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=171036

TBR=dcarney@chromium.org,haraken@chromium.org,jochen@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=359977
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=171053

[yurys, 2014-04-08 12:36:09]

Created Revert of Hook up gin platform to blink, and explicitly manage the main
thread isolate

[commit-bot: I haz the power, 2014-04-08 12:36:19]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/yurys@chromium.org/225023038/1

[commit-bot: I haz the power, 2014-04-08 12:36:35]

Change committed as 171053