[blink] Perspective layer should be considered fixed-pos container layer

[blink] Perspective layer should be considered fixed-pos container layer

This CL fixes a bug that fixed-position descendants skip its containing
block's perspective transform. Perspective layer (CompositedLayerMapping::
child_transform_layer_) should be considered fixed-pos container if
present.

BUG=714001
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2833233002
Cr-Commit-Position: refs/heads/master@{#467175}
(cherry picked from commit 25eaaeb522126f998e9bd83056f96a5ce3cc78c2)

Review-Url: https://codereview.chromium.org/2846313002 .
Cr-Commit-Position: refs/branch-heads/3071@{#299}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed: https://chromium.googlesource.com/chromium/src/+/425fee0e59a4cbaa0ff67a9f2702a269bcd1ac18

[trchen, 2017-04-28 18:49:59]

Description was changed from

==========
[blink] Perspective layer should be considered fixed-pos container layer

This CL fixes a bug that fixed-position descendants skip its containing
block's perspective transform. Perspective layer (CompositedLayerMapping::
child_transform_layer_) should be considered fixed-pos container if
present.

BUG=714001
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2833233002
Cr-Commit-Position: refs/heads/master@{#467175}
(cherry picked from commit 25eaaeb522126f998e9bd83056f96a5ce3cc78c2)
==========

to

==========
[blink] Perspective layer should be considered fixed-pos container layer

This CL fixes a bug that fixed-position descendants skip its containing
block's perspective transform. Perspective layer (CompositedLayerMapping::
child_transform_layer_) should be considered fixed-pos container if
present.

BUG=714001
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2833233002
Cr-Commit-Position: refs/heads/master@{#467175}
(cherry picked from commit 25eaaeb522126f998e9bd83056f96a5ce3cc78c2)

Review-Url: https://codereview.chromium.org/2846313002 .
Cr-Commit-Position: refs/branch-heads/3071@{#299}
Cr-Branched-From:
a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed:
https://chromium.googlesource.com/chromium/src/+/425fee0e59a4cbaa0ff67a9f2702...
==========

[trchen, 2017-04-28 18:50:01]

Committed patchset #1 (id:1) manually as
425fee0e59a4cbaa0ff67a9f2702a269bcd1ac18.