Use StringKeyframes to make CSS Animations responsive to style changes

Use StringKeyframes to make CSS Animations responsive to style changes

This patch switches from AnimatableValueKeyframe over to StringKeyframe
in CSS Animations. The only place that still uses AnimatableValueKeyframe
is transitions.

When an animated property is absent in the 0% or 100% keyframe, a neutral
keyframe is created which takes the value of the computed style. When
the computed style changes, the spec requires that the neutral keyframe
is updated accordingly to match the new style.

This patch also introduces behaviour changes for interpolating
SVG stroke-width, opacity and shape-image-transform. The new behaviours
of these interpolations in CSS Animations match that of Web Animations.

When there is a non-animation style change, neutral keyframes are updated.
Firefox handles this correctly, but IE11 doesn't.

BUG=361948
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192071

[alancutter (OOO until 2018), 2015-03-11 12:49:16]

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

[alancutter (OOO until 2018), 2015-03-11 12:49:16]

This is a rebase of Darren's patch to make length and other values responsive in
CSS animations: https://codereview.chromium.org/920653002
Performance issues with CSS length of more than one type have been resolved in
the common pixel+percentage case in: https://codereview.chromium.org/982913003
This change depends on https://codereview.chromium.org/995253002 landing first.

[alancutter (OOO until 2018), 2015-03-12 09:24:16]

The base LayoutStyle change has been moved to
https://codereview.chromium.org/999963003 to make this patch simpler.

[dstockwell, 2015-03-16 00:18:45]

lgtm

[Timothy Loh, 2015-03-16 00:49:42]

lgtm

https://codereview.chromium.org/948583003/diff/140001/Source/core/animation/D...
File Source/core/animation/DeferredLegacyStyleInterpolation.cpp (right):

https://codereview.chromium.org/948583003/diff/140001/Source/core/animation/D...
Source/core/animation/DeferredLegacyStyleInterpolation.cpp:28: // Snapshot
neutral values first because non-neutral values will mutate the
StyleResolverState.
Snapshot underlying values?

[alancutter (OOO until 2018), 2015-03-16 03:43:17]

The CQ bit was checked by alancutter@chromium.org

[commit-bot: I haz the power, 2015-03-16 03:43:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/948583003/140001

[alancutter (OOO until 2018), 2015-03-16 03:47:33]

The CQ bit was checked by alancutter@chromium.org

[alancutter (OOO until 2018), 2015-03-16 03:47:33]

The patchset sent to the CQ was uploaded after l-g-t-m from
dstockwell@chromium.org, timloh@chromium.org
Link to the patchset: https://codereview.chromium.org/948583003/#ps160001
(title: "Comment")

[commit-bot: I haz the power, 2015-03-16 03:47:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/948583003/160001

[alancutter (OOO until 2018), 2015-03-16 07:20:02]

The CQ bit was unchecked by alancutter@chromium.org

[alancutter (OOO until 2018), 2015-03-17 00:12:34]

https://codereview.chromium.org/948583003/diff/140001/Source/core/animation/D...
File Source/core/animation/DeferredLegacyStyleInterpolation.cpp (right):

https://codereview.chromium.org/948583003/diff/140001/Source/core/animation/D...
Source/core/animation/DeferredLegacyStyleInterpolation.cpp:28: // Snapshot
neutral values first because non-neutral values will mutate the
StyleResolverState.
On 2015/03/16 00:49:41, Timothy Loh wrote:
> Snapshot underlying values?

Done.

[alancutter (OOO until 2018), 2015-03-17 00:40:34]

https://codereview.chromium.org/948583003/diff/180001/Source/core/animation/c...
File Source/core/animation/css/CSSAnimations.cpp (right):

https://codereview.chromium.org/948583003/diff/180001/Source/core/animation/c...
Source/core/animation/css/CSSAnimations.cpp:378: 
This code has changed to fix a crash and might be worth a rereview.
Previously we were hitting ASSERT(!first.value() || !last.value()) in
KeyframeEffectModelBase::updateNeutralKeyframeAnimatableValues().

[alancutter (OOO until 2018), 2015-03-18 00:18:14]

The CQ bit was checked by alancutter@chromium.org

[alancutter (OOO until 2018), 2015-03-18 00:18:14]

The patchset sent to the CQ was uploaded after l-g-t-m from
dstockwell@chromium.org, timloh@chromium.org
Link to the patchset: https://codereview.chromium.org/948583003/#ps180001
(title: "Fix crash")

[commit-bot: I haz the power, 2015-03-18 00:20:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/948583003/180001

[commit-bot: I haz the power, 2015-03-18 00:35:35]

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

[commit-bot: I haz the power, 2015-03-18 00:35:36]

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/47916)

[alancutter (OOO until 2018), 2015-03-18 06:42:01]

The CQ bit was checked by alancutter@chromium.org

[alancutter (OOO until 2018), 2015-03-18 06:42:02]

The patchset sent to the CQ was uploaded after l-g-t-m from
dstockwell@chromium.org, timloh@chromium.org
Link to the patchset: https://codereview.chromium.org/948583003/#ps200001
(title: "Rebase")

[commit-bot: I haz the power, 2015-03-18 06:42:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/948583003/200001

[commit-bot: I haz the power, 2015-03-18 08:27:17]

Committed patchset #11 (id:200001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=192071