Prevent will-change:transform from changing the computed value of transform

Prevent will-change:transform from changing the computed value of transform

Elements styled with "will-change: transform" are supposed to behave like
transformed elements for the purposes of containing block creation, even
if their transform value is "none". The idea is that setting a transform on
such elements should be fast, involving only moving a composited layer
rather than changing layout. Currently, this is implemented by changing the
computed value of transform from 'none' to the identity transform. However,
changing the computed value of transform causes animations on such
elements to interpolate incorrectly, since interpolating from 'none' is not
equivalent to interpolating from the identity (in particular, interpolating
from the latter can lead to matrix decomposition rather than numerical
interpolation, producing visually different results).

This CL changes makes "will-change: transform" no longer change the
computed value of transform. Instead, this CL makes
ComputedStyle::hasTransformRelatedProperty return true for elements with
"will-change: transform".

BUG=525886
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201557

[alancutter (OOO until 2018), 2015-08-29 06:10:03]

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

[alancutter (OOO until 2018), 2015-08-29 06:10:04]

lgtm, thanks for the fix!

https://codereview.chromium.org/1318273003/diff/1/Source/core/style/ComputedS...
File Source/core/style/ComputedStyle.cpp (right):

https://codereview.chromium.org/1318273003/diff/1/Source/core/style/ComputedS...
Source/core/style/ComputedStyle.cpp:898: for (size_t i = 0; i <
rareNonInheritedData->m_willChange->m_properties.size(); ++i) {
Can we use for (const auto& property :
rareNonInheritedData->m_willChange->m_properties) here?

[ajuma, 2015-08-31 16:06:20]

Patchset #2 (id:20001) has been deleted

[ajuma, 2015-08-31 16:42:39]

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

[ajuma, 2015-08-31 16:43:57]

+timloh for OWNERS

https://codereview.chromium.org/1318273003/diff/1/Source/core/style/ComputedS...
File Source/core/style/ComputedStyle.cpp (right):

https://codereview.chromium.org/1318273003/diff/1/Source/core/style/ComputedS...
Source/core/style/ComputedStyle.cpp:898: for (size_t i = 0; i <
rareNonInheritedData->m_willChange->m_properties.size(); ++i) {
On 2015/08/29 06:10:04, alancutter wrote:
> Can we use for (const auto& property :
> rareNonInheritedData->m_willChange->m_properties) here?

Done.

[Timothy Loh, 2015-09-01 00:45:36]

On 2015/08/31 16:43:57, ajuma wrote:
> +timloh for OWNERS
> 
>
https://codereview.chromium.org/1318273003/diff/1/Source/core/style/ComputedS...
> File Source/core/style/ComputedStyle.cpp (right):
> 
>
https://codereview.chromium.org/1318273003/diff/1/Source/core/style/ComputedS...
> Source/core/style/ComputedStyle.cpp:898: for (size_t i = 0; i <
> rareNonInheritedData->m_willChange->m_properties.size(); ++i) {
> On 2015/08/29 06:10:04, alancutter wrote:
> > Can we use for (const auto& property :
> > rareNonInheritedData->m_willChange->m_properties) here?
> 
> Done.

lgtm

[ajuma, 2015-09-01 13:03:59]

The CQ bit was checked by ajuma@chromium.org

[ajuma, 2015-09-01 13:03:59]

The patchset sent to the CQ was uploaded after l-g-t-m from
alancutter@chromium.org
Link to the patchset: https://codereview.chromium.org/1318273003/#ps60001
(title: " ")

[commit-bot: I haz the power, 2015-09-01 13:04:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1318273003/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1318273003/60001

[commit-bot: I haz the power, 2015-09-01 14:38:58]

Committed patchset #3 (id:60001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201557