Revert of Remove GetAttributes from the mix to avoid another virtual dispatch.

Revert of Remove GetAttributes from the mix to avoid another virtual dispatch. (patchset #2 id:40001 of https://codereview.chromium.org/1175973002/)

Reason for revert:
It broke webkit_unit_tests

Original issue's description:
> Remove GetAttributes from the mix to avoid another virtual dispatch.
>
> BUG=chromium:495949, v8:4137
> LOG=n
>
> Committed: https://crrev.com/2269b8b5a696bf4eef13590093151bff624d4175
> Cr-Commit-Position: refs/heads/master@{#28953}

TBR=verwaest@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:495949, v8:4137
Committed: https://crrev.com/ae639d2ad646237e2f413259a0f116845ef96440
Cr-Commit-Position: refs/heads/master@{#28958}

[Igor Sheludko, 2015-06-11 17:25:01]

Created Revert of Remove GetAttributes from the mix to avoid another virtual
dispatch.

[commit-bot: I haz the power, 2015-06-11 17:25:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1179933002/1

[commit-bot: I haz the power, 2015-06-11 17:25:28]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-11 17:25:43]

Patchset 1 (id:??) landed as
https://crrev.com/ae639d2ad646237e2f413259a0f116845ef96440
Cr-Commit-Position: refs/heads/master@{#28958}

[Toon Verwaest, 2015-06-11 20:16:53]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1182603002/ by verwaest@chromium.org.

The reason for reverting is: Reland, this didn't break anything..