Re-enable layer squashing

Re-enable layer squashing

We've fixed all the know bugs. Hopefully this time it will stick. If you find
that this CL caused a regression, please mark the bug as blocking
http://crbug.com/365701

BUG=365701
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=173696

[chrishtr, 2014-05-09 00:49:02]

The CQ bit was checked by chrishtr@chromium.org

[commit-bot: I haz the power, 2014-05-09 00:50:48]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/abarth@chromium.org/267343005/1

[commit-bot: I haz the power, 2014-05-09 00:50:49]

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

[commit-bot: I haz the power, 2014-05-09 00:50:49]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer or
a provisional committer, _not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[chrishtr, 2014-05-09 00:51:15]

lgtm

[commit-bot: I haz the power, 2014-05-09 01:09:01]

Change committed as 173696

[abarth-chromium, 2014-05-09 05:26:21]

A revert of this CL has been created in
https://codereview.chromium.org/279703002/ by abarth@chromium.org.

The reason for reverting is: We still have open layer squashing bugs..