Revert of Oilpan: Refactor the way we calculate heap statistics

Revert of Oilpan: Refactor the way we calculate heap statistics (patchset #12 id:220001 of https://codereview.chromium.org/723513002/)

Reason for revert:
[Sheriff] Breaks compilation on win x64:
http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Win%20x64%20Builder/builds/25605

Original issue's description:
> Oilpan: Refactor the way we calculate heap statistics
> 
> This is a preparation for implementing incremental sweeping.
> 
> - Remove ThreadState::HeapStats.
> 
> - Introduce Heap::allocatedSpace, Heap::allocatedObjectSize and Heap::liveObjectSize.
> 
> --- Heap::allocatedSpace keeps track of the size of allocated space.
> 
> --- Heap::allocatedObjectSize keeps track of the size of objects allocated since the last GC.
> 
> --- Heap::liveObjectSize keeps track of the size of marked objects in the last GC.
> 
> - Adds a couple of atomic instructions to Atomics.h to update the Heap metrics atomically.
> 
> - This CL fixes the issue that shouldGC() determines GC timing only based on the size of the current thread heap. After this CL, shouldGC() determines GC timing based on the entire heap.
> 
> - Rename getStatsForTesting() to objectPayloadSizeForTesting().
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=185513

TBR=oilpan-reviews@chromium.org,sigbjornf@opera.com,tkent@chromium.org,vegorov@chromium.org,haraken@chromium.org
NOTREECHECKS=true
NOTRY=true

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=185514

[Michael Achenbach, 2014-11-18 11:48:17]

Created Revert of Oilpan: Refactor the way we calculate heap statistics

[commit-bot: I haz the power, 2014-11-18 11:49:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/738773003/1

[commit-bot: I haz the power, 2014-11-18 11:49:45]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=185514

[haraken, 2014-11-18 11:51:18]

LGTM, thanks for the revert!