Turn on property tree verification for layout tests

Turn on property tree verification for layout tests

This add DCHECKs when running all layout tests to verify that the new
property tree approach generates the same results as the old calculate
draw properties approach.

R=mkwst@chromium.org,vollick@chromium.org

Committed: https://crrev.com/d560578bca1374425e338f1623ad1afa63aa4e2b
Cr-Commit-Position: refs/heads/master@{#321705}

[jochen (gone - plz use gerrit), 2015-03-09 17:55:08]

jochen@chromium.org changed reviewers:
+ mkwst@chromium.org
- mkwest@chromium.org

[Mike West, 2015-03-10 10:17:41]

The bot is very unhappy. If it's just the bot, then LGTM! Land it! If the bot is
telling you something about the flag's behavior, then probably fix the behavior,
then land the flag. :)

[Ian Vollick, 2015-03-10 13:31:16]

On 2015/03/10 10:17:41, Mike West (OOO) wrote:
> The bot is very unhappy. If it's just the bot, then LGTM! Land it! If the bot
is
> telling you something about the flag's behavior, then probably fix the
behavior,
> then land the flag. :)

There's still a correctness bug with property trees to fix
(https://codereview.chromium.org/994843002/), but once that's in, this should be
good to land. (Evidence: I put the fix in a patch along with this change and
it's green https://codereview.chromium.org/985283002/).

[Ian Vollick, 2015-03-21 15:23:51]

On 2015/03/10 13:31:16, vollick wrote:
> On 2015/03/10 10:17:41, Mike West (OOO) wrote:
> > The bot is very unhappy. If it's just the bot, then LGTM! Land it! If the
bot
> is
> > telling you something about the flag's behavior, then probably fix the
> behavior,
> > then land the flag. :)
> 
> There's still a correctness bug with property trees to fix
> (https://codereview.chromium.org/994843002/), but once that's in, this should
be
> good to land. (Evidence: I put the fix in a patch along with this change and
> it's green https://codereview.chromium.org/985283002/).

This should now be ready to go!

[Ian Vollick, 2015-03-21 15:24:37]

The CQ bit was checked by vollick@chromium.org

[commit-bot: I haz the power, 2015-03-21 15:24:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/981753002/1

[commit-bot: I haz the power, 2015-03-22 05:14:29]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-22 05:15:56]

Patchset 1 (id:??) landed as
https://crrev.com/d560578bca1374425e338f1623ad1afa63aa4e2b
Cr-Commit-Position: refs/heads/master@{#321705}