Re-enable property tree verification for layout tests

Re-enable property tree verification for layout tests

Property tree verification was inadvertently disabled by
http://crrev.com/976553002.

This CL re-enables it.

Committed: https://crrev.com/e1d84122d35e432848f4f8e9cc766cd40c6d88fb
Cr-Commit-Position: refs/heads/master@{#324409}

[ajuma, 2015-04-08 22:53:55]

ajuma@chromium.org changed reviewers:
+ mkwst@chromium.org

[ajuma, 2015-04-08 22:56:37]

A regression crept in while verification was turned off; a fix for that is in
the CQ (http://crrev.com/1077433003) and will need to land before this does.

[Mike West, 2015-04-09 04:46:49]

LGTM, assuming the bots are happy.

[Ian Vollick, 2015-04-09 10:50:52]

The CQ bit was checked by vollick@chromium.org

[commit-bot: I haz the power, 2015-04-09 10:51:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1068383002/1

[commit-bot: I haz the power, 2015-04-09 11:01:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-09 11:01:53]

Patchset 1 (id:??) landed as
https://crrev.com/e1d84122d35e432848f4f8e9cc766cd40c6d88fb
Cr-Commit-Position: refs/heads/master@{#324409}