Fix clipping of squashed sibling layers with border radius masks

Fix clipping of squashed sibling layers with border radius masks

Merge to M-59 branch.

When a composited element with a border-radius overflow parent
has border radius and overflows itself, the element's clip rect
is included on the mask layer for the parent, which causes incorrect
clipping of sibling content.

Unfortunately a ref test fails due to a single pixel different on
the border radius.

TBR=chrishtr@chromium.org
BUG=709533
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2821733002
Cr-Original-Commit-Position: refs/heads/master@{#465028}
Review-Url: https://codereview.chromium.org/2825743002 .
Cr-Commit-Position: refs/branch-heads/3071@{#31}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed: https://chromium.googlesource.com/chromium/src/+/eb714ee2495710bfdabad870fd9be463a3fc61c8

[Stephen Chennney, 2017-04-18 14:10:53]

Description was changed from

==========
Fix clipping of squashed sibling layers with border radius masks

Merge to M-59 branch.

When a composited element with a border-radius overflow parent
has border radius and overflows itself, the element's clip rect
is included on the mask layer for the parent, which causes incorrect
clipping of sibling content.

Unfortunately a ref test fails due to a single pixel different on
the border radius.

R=chrishtr@chromium.org
BUG=709533
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2821733002
Cr-Commit-Position: refs/heads/master@{#465028}
==========

to

==========
Fix clipping of squashed sibling layers with border radius masks

Merge to M-59 branch.

When a composited element with a border-radius overflow parent
has border radius and overflows itself, the element's clip rect
is included on the mask layer for the parent, which causes incorrect
clipping of sibling content.

Unfortunately a ref test fails due to a single pixel different on
the border radius.

TBR=chrishtr@chromium.org
BUG=709533
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2821733002
Cr-Commit-Position: refs/heads/master@{#465028}
==========

[Stephen Chennney, 2017-04-18 14:11:34]

Description was changed from

==========
Fix clipping of squashed sibling layers with border radius masks

Merge to M-59 branch.

When a composited element with a border-radius overflow parent
has border radius and overflows itself, the element's clip rect
is included on the mask layer for the parent, which causes incorrect
clipping of sibling content.

Unfortunately a ref test fails due to a single pixel different on
the border radius.

TBR=chrishtr@chromium.org
BUG=709533
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2821733002
Cr-Commit-Position: refs/heads/master@{#465028}
==========

to

==========
Fix clipping of squashed sibling layers with border radius masks

Merge to M-59 branch.

When a composited element with a border-radius overflow parent
has border radius and overflows itself, the element's clip rect
is included on the mask layer for the parent, which causes incorrect
clipping of sibling content.

Unfortunately a ref test fails due to a single pixel different on
the border radius.

TBR=chrishtr@chromium.org
BUG=709533
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2821733002
Cr-Original-Commit-Position: refs/heads/master@{#465028}
Review-Url: https://codereview.chromium.org/2825743002 .
Cr-Commit-Position: refs/branch-heads/3071@{#31}
Cr-Branched-From:
a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed:
https://chromium.googlesource.com/chromium/src/+/eb714ee2495710bfdabad870fd9b...
==========

[Stephen Chennney, 2017-04-18 14:11:35]

Committed patchset #1 (id:1) manually as
eb714ee2495710bfdabad870fd9be463a3fc61c8 (presubmit successful).