Unreviewed, rolling r166248 back in.

Turns out r166070 didn't cause a 2% performance loss in page load times

Reverted changeset:

Unreviewed, rolling out r166126.
Rollout r166126 in prepartion to roll out prerequisite r166070


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@166415 268f45cc-cd09-0410-ab3c-d52691b4dbfc
16 files changed