Remove duplicated CSSValueNone checks

Remove duplicated CSSValueNone checks

In these cases instead of duplicated code to create the None identifier, use
the validPrimitive machinery instead.

BUG=404023
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192529

[rwlbuis, 2015-03-24 19:37:31]

rob.buis@samsung.com changed reviewers:
+ timloh@chromium.org

[rwlbuis, 2015-03-24 19:37:32]

PTAL.

[Timothy Loh, 2015-03-24 23:41:05]

ok, lgtm

[rwlbuis, 2015-03-25 00:02:46]

The CQ bit was checked by rob.buis@samsung.com

[commit-bot: I haz the power, 2015-03-25 00:03:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/893193005/1

[commit-bot: I haz the power, 2015-03-25 03:53:52]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-03-25 03:53:53]

Try jobs failed on following builders:
  mac_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/48810)

[rwlbuis, 2015-03-25 11:05:26]

The CQ bit was checked by rob.buis@samsung.com

[commit-bot: I haz the power, 2015-03-25 11:05:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/893193005/1

[commit-bot: I haz the power, 2015-03-25 12:32:47]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=192529