Simplify the paint invalidation bits.

Simplify the paint invalidation bits.

The only thing they're used for now is to clear the
background obscuration state on RenderBox. They're
also used in RenderLayerModelObject::styleWillChange,
but that usage seems like a huge premature optimization.
Unfortunately, the RenderBox one walks up the ancestor
chain, so it's likely a necessary performance optimization.

R=esprehn@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/5738b6bebcd8b6a85911523b47b705420c5d3c58

[ojan, 2015-01-15 01:56:43]

https://codereview.chromium.org/851033002/diff/1/sky/engine/core/rendering/Re...
File sky/engine/core/rendering/RenderObject.cpp (left):

https://codereview.chromium.org/851033002/diff/1/sky/engine/core/rendering/Re...
sky/engine/core/rendering/RenderObject.cpp:1222: if (diff.textOrColorChanged()
&& !diff.needsPaintInvalidation()
I believe we don't need this anymore. If text or color changes it doesn't affect
whether the background is obscured or not, which is the only thing this bool
affects at the moment.

https://codereview.chromium.org/851033002/diff/1/sky/engine/core/rendering/Re...
File sky/engine/core/rendering/RenderObject.cpp (right):

https://codereview.chromium.org/851033002/diff/1/sky/engine/core/rendering/Re...
sky/engine/core/rendering/RenderObject.cpp:1204: if (!isText() &&
This is the same as the old code, except I merged the transform/opacity/zindex
cases to avoid needless branching.

https://codereview.chromium.org/851033002/diff/1/sky/engine/core/rendering/st...
File sky/engine/core/rendering/style/RenderStyle.cpp (left):

https://codereview.chromium.org/851033002/diff/1/sky/engine/core/rendering/st...
sky/engine/core/rendering/style/RenderStyle.cpp:291:
diff.setNeedsPaintInvalidationObject();
All needsPaintInvalidation does is clear the background obscuration status,
which happens during layout anyways. So we don't need to ever set both bits.

[ojan, 2015-01-15 20:47:44]

ojan@chromium.org changed reviewers:
+ esprehn@chromium.org

[esprehn, 2015-01-15 20:52:49]

lgtm

[ojan, 2015-01-15 21:02:07]

Committed patchset #2 (id:20001) manually as
5738b6bebcd8b6a85911523b47b705420c5d3c58 (presubmit successful).