Revert of Add WeakMap to v8.h

Revert of Add WeakMap to v8.h (patchset #3 id:40001 of https://codereview.chromium.org/886473005/)

Reason for revert:
Breaks Win32 build bot.

Original issue's description:
> Add WeakMap to v8.h
> 
> A new map wich references its keys weakly is added to v8.h. Internally it uses the same storage as JSWeakMap but doesn't depend on the JavaScript part of WeakMap implementation in weak-collection.js, hence it can be instantiated without entering any context.
> 
> BUG=chromium:437416
> LOG=Y
> 
> Committed: https://crrev.com/37d4c57630636f21e3add8d3d1c7c978ff5fc8e0
> Cr-Commit-Position: refs/heads/master@{#26401}

TBR=jochen@chromium.org,mstarzinger@chromium.org,yurys@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:437416

[vogelheim, 2015-02-03 14:41:25]

Created Revert of Add WeakMap to v8.h

[commit-bot: I haz the power, 2015-02-03 14:42:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/875113004/1

[commit-bot: I haz the power, 2015-02-03 14:43:45]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-02-03 14:43:46]

Failed to apply the patch.

[commit-bot: I haz the power, 2015-02-03 14:43:48]

The CQ bit was unchecked by commit-bot@chromium.org