Switching CSS Variables over to RuntimeEnabledFeatures

Switching CSS Variables over to RuntimeEnabledFeatures

Taking the CSS Variables flag out of InternalSettings and Settings
and using RuntimeEnabledFeatures instead.


BUG=239748
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=150468

[alancutter (OOO until 2018), 2013-05-10 08:07:38]

This Chromium change MUST land before this patch can land in Blink:
https://codereview.chromium.org/14683006/

[eseidel, 2013-05-10 08:13:32]

lgtm

[commit-bot: I haz the power, 2013-05-15 23:37:29]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/alancutter@chromium.org/14987004/1

[commit-bot: I haz the power, 2013-05-16 00:04:53]

Retried try job too often on blink_bare_presubmit for step(s) presubmit
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=blink_bare...

[abarth-chromium, 2013-05-16 00:42:59]

API change LGTM

[commit-bot: I haz the power, 2013-05-16 00:43:24]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/alancutter@chromium.org/14987004/1

[commit-bot: I haz the power, 2013-05-16 01:35:10]

Change committed as 150468

[eseidel, 2013-05-16 05:03:14]

fast/css/parsing-expr-error-recovery.html appears to hit an ASSERT in debug. 
This is the only change on the blame-list.

[eseidel, 2013-05-16 05:13:44]

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=fas...