Make AnimatedStyleBuilder value rounding consistent with StyleBuilder

Make AnimatedStyleBuilder value rounding consistent with StyleBuilder

For the following properties the StyleBuilder uses roundForImpreciseConversion()
while the AnimatedStyleBuilder uses round().
 - border-width
 - outline-width
 - -webkit-column-count
 - -webkit-column-rule-width

This change updates AnimatedStyleBuilder to use rounding that is
consistent with the StyleBuilder.

BUG=437696
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200629

[alancutter (OOO until 2018), 2015-08-03 05:48:38]

alancutter@chromium.org changed reviewers:
+ timloh@chromium.org

[dstockwell, 2015-08-13 07:56:38]

dstockwell@chromium.org changed reviewers:
+ dstockwell@chromium.org

[dstockwell, 2015-08-13 07:56:39]

lgtm

[alancutter (OOO until 2018), 2015-08-17 05:42:17]

The CQ bit was checked by alancutter@chromium.org

[commit-bot: I haz the power, 2015-08-17 05:42:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1259803007/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1259803007/1

[commit-bot: I haz the power, 2015-08-17 07:16:45]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200629