Fix 50% flip handling of CSS Animations using CSS wide keywords

Fix 50% flip handling of CSS Animations using CSS wide keywords

CSS Animations of certain properties [1] were handling CSS wide keywords
like inherit as 50% flip cases instead of smoothly interpolating when
appropriate.

This patch makes all CSS wide keywords fall back to either
LegacyStyleInterpolation or DeferredLegacyStyleInterpolation
before attempting *StyleInterpolation conversion which fixes
smooth interpolation of these keywords.

[1]
border-image-slice
list-style-image
-webkit-mask-box-image
-webkit-mask-box-image-source

BUG=437696
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=199936

[alancutter (OOO until 2018), 2015-07-30 05:44:37]

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

[shans, 2015-08-03 10:44:21]

On 2015/07/30 05:44:38, alancutter wrote:

LGTM

(I thought from the description that you were falling all the way back to the
original AV pipeline, which confused me for a while :))

[alancutter (OOO until 2018), 2015-08-04 02:55:24]

On 2015/08/03 at 10:44:21, shans wrote:
> On 2015/07/30 05:44:38, alancutter wrote:
> 
> LGTM
> 
> (I thought from the description that you were falling all the way back to the
original AV pipeline, which confused me for a while :))

Updated description to refer to LegacyStyleInterpolation and
DeferredLegacyStyleInterpolation specifically.

[alancutter (OOO until 2018), 2015-08-04 02:55:32]

The CQ bit was checked by alancutter@chromium.org

[commit-bot: I haz the power, 2015-08-04 02:55:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1262283002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1262283002/20001

[commit-bot: I haz the power, 2015-08-04 04:17:56]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=199936