Fix asserts when updating shouldPaint for floating objects.

Fix asserts when updating shouldPaint for floating objects.

The assert would trigger when loading fast/overflow/overflow-float-stacking.html if
--enable-prefer-compositing-to-lcd-text was true, because
LayoutBlockFlow::setAncestorShouldPaintFloatingObject asserted that the floating
object is not self-painting. But that method could be called when transitioning
from not-self-painting to self-painting, so the assert appears bogus.

Committed: https://crrev.com/c66072d18271173b0b61e943c65c0c95ea2afb4b
Cr-Commit-Position: refs/heads/master@{#408527}

[chrishtr, 2016-07-28 20:47:58]

Description was changed from

==========
none

BUG=
==========

to

==========
Fix asserts when updating shouldPaint for floating objects.

The assert would trigger when loading fast/overflow/overflow-float-stacking.html
if
--enable-prefer-compositing-to-lcd-text was true, because
LayoutBlockFlow::setAncestorShouldPaintFloatingObject asserted that the floating
object is not self-painting. But that method could be called when transitioning
from not-self-painting to self-painting, so the assert appears bogus.
==========

[chrishtr, 2016-07-28 20:48:43]

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

[chrishtr, 2016-07-28 20:48:55]

The CQ bit was checked by chrishtr@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-07-28 20:49:22]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Xianzhu, 2016-07-28 20:57:50]

lgtm

[commit-bot: I haz the power, 2016-07-29 00:08:06]

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

[commit-bot: I haz the power, 2016-07-29 00:08:07]

Dry run: This issue passed the CQ dry run.

[chrishtr, 2016-07-29 00:13:57]

The CQ bit was checked by chrishtr@chromium.org

[commit-bot: I haz the power, 2016-07-29 00:14:25]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-29 00:18:08]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-07-29 00:21:06]

Description was changed from

==========
Fix asserts when updating shouldPaint for floating objects.

The assert would trigger when loading fast/overflow/overflow-float-stacking.html
if
--enable-prefer-compositing-to-lcd-text was true, because
LayoutBlockFlow::setAncestorShouldPaintFloatingObject asserted that the floating
object is not self-painting. But that method could be called when transitioning
from not-self-painting to self-painting, so the assert appears bogus.
==========

to

==========
Fix asserts when updating shouldPaint for floating objects.

The assert would trigger when loading fast/overflow/overflow-float-stacking.html
if
--enable-prefer-compositing-to-lcd-text was true, because
LayoutBlockFlow::setAncestorShouldPaintFloatingObject asserted that the floating
object is not self-painting. But that method could be called when transitioning
from not-self-painting to self-painting, so the assert appears bogus.

Committed: https://crrev.com/c66072d18271173b0b61e943c65c0c95ea2afb4b
Cr-Commit-Position: refs/heads/master@{#408527}
==========

[commit-bot: I haz the power, 2016-07-29 00:21:09]

Patchset 1 (id:??) landed as
https://crrev.com/c66072d18271173b0b61e943c65c0c95ea2afb4b
Cr-Commit-Position: refs/heads/master@{#408527}