Add no-op disable-impl-side-painting flag to one suite

Add no-op disable-impl-side-painting flag to one suite

The virtual/deferred test suite needs to exist until impl-side painting
is turned on everywhere.  However, it would be nice to make all new
directories have impl-side painting by default.

Currently, the state is that:
  * Impl-side painting is enabled by default.
  * The enable flag overrides the disable flag.
  * Content shell passes the disable flag.
  * All test suites but deferred pass the enable flag.

This patch adds a redundant disable flag to the deferred suite, which
will allow the content shell flag to be removed and then the enable flag
on all test suites to be removed afterwards.

R=chrishtr@chromium.org
BUG=381919
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=188710

[chrishtr, 2015-01-21 00:32:28]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2015-01-21 00:32:28]

lgtm

[commit-bot: I haz the power, 2015-01-21 00:32:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/818233003/1

[commit-bot: I haz the power, 2015-01-21 05:02:41]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=188710