Use non-zero values when testing neutral keyframe correctness

Use non-zero values when testing neutral keyframe correctness

Neutral keyframes represent the underlying CSS value. This can be
implemented internally by adding zero to the underlying value.
This test should avoid using zero for an underlying value to ensure
the "add zero" neutral keyframe implementation is not accidentally
replacing with zero.

BUG=437696
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197960

[alancutter (OOO until 2018), 2015-06-29 01:33:52]

alancutter@chromium.org changed reviewers:
+ dstockwell@chromium.org, shans@chromium.org

[shans, 2015-06-29 02:29:26]

lgtm

[alancutter (OOO until 2018), 2015-06-29 04:06:28]

The CQ bit was checked by alancutter@chromium.org

[commit-bot: I haz the power, 2015-06-29 04:06:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1214083002/1

[commit-bot: I haz the power, 2015-06-29 05:26:35]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197960