Revert of Remove slots that point to unboxed doubles from the StoreBuffer/SlotsBuffer. (patchset #4…

Revert of Remove slots that point to unboxed doubles from the StoreBuffer/SlotsBuffer. (patchset #4 id:230001 of https://codereview.chromium.org/957273002/)

Reason for revert:
It caused a lot of Canary crashes.

Original issue's description:
> Remove slots that point to unboxed doubles from the StoreBuffer/SlotsBuffer.
>
> The problem is that tagged slot could become a double slot after migrating of an object to another map with "shifted" fields (for example as a result of generalizing immutable data property to a data field).
> This CL also adds useful machinery that helps triggering incremental write barriers.
>
> BUG=chromium:454297
> LOG=Y
>
> Committed: https://crrev.com/9633ebabd405c264d33f603f8798c31f59418dcd
> Cr-Commit-Position: refs/heads/master@{#27054}

TBR=verwaest@chromium.org,hpayer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:454297
Committed: https://crrev.com/67a02321c2e968603c538ab286a6175cdf99b674
Cr-Commit-Position: refs/heads/master@{#27063}

[Igor Sheludko, 2015-03-09 10:10:54]

Committed patchset #1 (id:1) manually as
67a02321c2e968603c538ab286a6175cdf99b674.

[commit-bot: I haz the power, 2015-03-09 10:10:54]

Patchset 1 (id:??) landed as
https://crrev.com/67a02321c2e968603c538ab286a6175cdf99b674
Cr-Commit-Position: refs/heads/master@{#27063}

[Hannes Payer (out of office), 2015-03-09 12:37:16]

LGTM