Don't include contents visual overflow into paint invalidation rect

Don't include contents visual overflow into paint invalidation rect

Now we always invalidate any object needing repaint, so we never need
the paint invalidation rect of an ancestor to cover descendants.

BUG=436198
Committed: https://crrev.com/638c1a24dc8fdcceb5b5f4acd9d03d3a09b9cfa3
Cr-Commit-Position: refs/heads/master@{#392652}

[Xianzhu, 2016-05-09 19:10:25]

Description was changed from

==========
Ignore empty rects when collecting visual overflow

We used LayoutRect::uniteEvenIfEmpty() to unite visual overflow rects.
We did ignore empty rects in LayoutBox::addSelfVisualOverflowRect()
and addContentsVisualOverflowRect(), but we didn't ignore empty
initial visual overflow (border box rect).

As empty rects are invisible, ignore them in visual overflow.

BUG=436198
==========

to

==========
Don't include contents visual overflow into paint invalidation rect

Now we always invalidate any object needing repaint, so we never need
the paint invalidation rect of an ancestor to cover descendants. 

BUG=436198
==========

[Xianzhu, 2016-05-09 19:10:38]

wangxianzhu@chromium.org changed reviewers:
+ chrishtr@chromium.org

[chrishtr, 2016-05-09 21:57:21]

lgtm

[Xianzhu, 2016-05-10 03:40:43]

The CQ bit was checked by wangxianzhu@chromium.org

[Xianzhu, 2016-05-10 03:40:44]

The patchset sent to the CQ was uploaded after l-g-t-m from
chrishtr@chromium.org
Link to the patchset: https://codereview.chromium.org/1929413002/#ps60001
(title: "NeedsRebaseline")

[commit-bot: I haz the power, 2016-05-10 03:40:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1929413002/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1929413002/60001

[commit-bot: I haz the power, 2016-05-10 04:47:16]

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

[commit-bot: I haz the power, 2016-05-10 04:47:16]

Try jobs failed on following builders:
  linux_chromium_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[Xianzhu, 2016-05-10 16:48:22]

The CQ bit was checked by wangxianzhu@chromium.org

[Xianzhu, 2016-05-10 16:48:22]

The patchset sent to the CQ was uploaded after l-g-t-m from
chrishtr@chromium.org
Link to the patchset: https://codereview.chromium.org/1929413002/#ps80001
(title: " ")

[commit-bot: I haz the power, 2016-05-10 16:48:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1929413002/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1929413002/80001

[commit-bot: I haz the power, 2016-05-10 18:21:40]

Description was changed from

==========
Don't include contents visual overflow into paint invalidation rect

Now we always invalidate any object needing repaint, so we never need
the paint invalidation rect of an ancestor to cover descendants. 

BUG=436198
==========

to

==========
Don't include contents visual overflow into paint invalidation rect

Now we always invalidate any object needing repaint, so we never need
the paint invalidation rect of an ancestor to cover descendants. 

BUG=436198
==========

[commit-bot: I haz the power, 2016-05-10 18:21:41]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2016-05-10 18:23:27]

Description was changed from

==========
Don't include contents visual overflow into paint invalidation rect

Now we always invalidate any object needing repaint, so we never need
the paint invalidation rect of an ancestor to cover descendants. 

BUG=436198
==========

to

==========
Don't include contents visual overflow into paint invalidation rect

Now we always invalidate any object needing repaint, so we never need
the paint invalidation rect of an ancestor to cover descendants.

BUG=436198

Committed: https://crrev.com/638c1a24dc8fdcceb5b5f4acd9d03d3a09b9cfa3
Cr-Commit-Position: refs/heads/master@{#392652}
==========

[commit-bot: I haz the power, 2016-05-10 18:23:28]

Patchset 5 (id:??) landed as
https://crrev.com/638c1a24dc8fdcceb5b5f4acd9d03d3a09b9cfa3
Cr-Commit-Position: refs/heads/master@{#392652}

[Zhenyao Mo, 2016-05-12 17:15:28]

A revert of this CL (patchset #5 id:80001) has been created in
https://codereview.chromium.org/1973023002/ by zmo@chromium.org.

The reason for reverting is: caused rendering regression, see crbug.com/611272.