Revert of Oilpan: catch some self-referential leaks (main thread.)

Revert of Oilpan: catch some self-referential leaks (main thread.) (patchset #8 id:140001 of https://codereview.chromium.org/1275863002/ )

Reason for revert:
Multiple failures on Win Oilpan Debug bot: http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Win%20Oilpan%20%28dbg%29/builds/2018

Original issue's description:
> Oilpan: catch some self-referential leaks (main thread.)
> 
> Track the number of SelfKeepAlive<>s that are currently active on
> the main thread, so as to be able to detect if any remains on
> shutdown. A clear indication of a leak, if so.
> 
> Also add some debugging support for detecting thread shutdown
> leaks due to Persistent<>s not being released; see
> PersistentRegion::dumpLivePersistents() and ThreadState::cleanup().
> 
> R=haraken
> BUG=420515
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200174

TBR=oilpan-reviews@chromium.org,haraken@chromium.org,sigbjornf@opera.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=420515
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200195

[Justin Novosad, 2015-08-07 21:00:59]

Created Revert of Oilpan: catch some self-referential leaks (main thread.)

[commit-bot: I haz the power, 2015-08-07 21:01:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1272573008/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1272573008/1

[commit-bot: I haz the power, 2015-08-07 21:02:15]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200195

[sof, 2015-08-08 05:26:36]

might as well for the time being, lgtm.

A step too far perhaps to have this assert check in place for these unruly unit
tests, but if anyone wants to chase them out, feel free to land this CL in
parallel with doing so.