Prepare LayoutTests for making data: urls async

Prepare LayoutTests for making data: urls async

I've just about given up on making data urls async
for now, given the trouble I've had with browser_tests.
But I'm at least going to commit these changes
which prepare LayoutTests for making data urls async
at a future time.

BUG=308321, 365509
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=172789

[abarth-chromium, 2014-04-28 18:19:35]

lgtm

[abarth-chromium, 2014-04-28 18:19:38]

The CQ bit was checked by abarth@chromium.org

[commit-bot: I haz the power, 2014-04-28 18:20:08]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/eseidel@chromium.org/258713015/1

[eseidel, 2014-04-28 18:50:47]

The CQ bit was unchecked by eseidel@chromium.org

[eseidel, 2014-04-28 18:50:47]

The CQ bit was checked by eseidel@chromium.org

[commit-bot: I haz the power, 2014-04-28 18:51:13]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/eseidel@chromium.org/258713015/1

[commit-bot: I haz the power, 2014-04-28 19:20:30]

Change committed as 172789