Load callback data from weak cell instead of embedding it in handler.

Load callback data from weak cell instead of embedding it in handler.

BUG=v8:3629
LOG=N

Committed: https://crrev.com/3ea4ca9dbffdbd878ae5d2d2960875ab1acf0b44
Cr-Commit-Position: refs/heads/master@{#26358}

[ulan, 2015-01-30 13:08:52]

ulan@chromium.org changed reviewers:
+ dcarney@chromium.org

[ulan, 2015-01-30 13:08:53]

PTAL

[dcarney, 2015-01-30 13:58:04]

lgtm

[ulan, 2015-01-30 14:01:27]

The CQ bit was checked by ulan@chromium.org

[commit-bot: I haz the power, 2015-01-30 14:01:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/877243004/20001

[commit-bot: I haz the power, 2015-01-30 14:31:23]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-30 14:31:38]

Patchset 2 (id:??) landed as
https://crrev.com/3ea4ca9dbffdbd878ae5d2d2960875ab1acf0b44
Cr-Commit-Position: refs/heads/master@{#26358}