[Blink>Paint] Document element cannot always omit isolation

[Blink>Paint] Document element cannot always omit isolation

The previous assumption that nothing can be the backdrop of the document
element's stacking context was incorrect, because document background doesn't
paint as a part of the stacking context but as canvas backdrop instead.

Note that only non-composited blending elements are affected by this bug.
This CL changes behavior to match composited code path, which also matches
Firefox behavior.

BUG=673597
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Committed: https://crrev.com/cf97fd35cae7ca6fae58cff6eea2f6cc59716171
Cr-Commit-Position: refs/heads/master@{#438298}

[trchen, 2016-12-13 02:29:36]

Description was changed from

==========
[Blink>Paint] Document element cannot always omit isolation

The previous assumption that nothing can be the backdrop of the document
element's stacking context was incorrect, because document background doesn't
paint as a part of the stacking context but as canvas backdrop instead.

Note that only non-composited blending elements are affected by this bug.
This CL changes behavior to match composited code path, which also matches
Firefox behavior.

BUG=673597
==========

to

==========
[Blink>Paint] Document element cannot always omit isolation

The previous assumption that nothing can be the backdrop of the document
element's stacking context was incorrect, because document background doesn't
paint as a part of the stacking context but as canvas backdrop instead.

Note that only non-composited blending elements are affected by this bug.
This CL changes behavior to match composited code path, which also matches
Firefox behavior.

BUG=673597
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[trchen, 2016-12-13 02:29:53]

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

[trchen, 2016-12-13 02:30:02]

trchen@chromium.org changed reviewers:
+ pdr@chromium.org

[commit-bot: I haz the power, 2016-12-13 02:30:41]

Dry run: 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, 2016-12-13 04:30:57]

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

[commit-bot: I haz the power, 2016-12-13 04:30:58]

Dry run: This issue passed the CQ dry run.

[pdr., 2016-12-13 04:52:01]

Traced back to https://src.chromium.org/viewvc/blink?view=rev&revision=160444,
seems like it was an incomplete fix.

LGTM

[trchen, 2016-12-13 21:41:56]

The CQ bit was checked by trchen@chromium.org

[commit-bot: I haz the power, 2016-12-13 21:42:37]

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, 2016-12-13 21:53:44]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1481665316322210, "parent_rev":
"d4a59da1b0b492d79624fcef4e6ab4641836ab39", "commit_rev":
"988dffed8e8ad89871843b7283ef7044c631576a"}

[commit-bot: I haz the power, 2016-12-13 21:54:10]

Description was changed from

==========
[Blink>Paint] Document element cannot always omit isolation

The previous assumption that nothing can be the backdrop of the document
element's stacking context was incorrect, because document background doesn't
paint as a part of the stacking context but as canvas backdrop instead.

Note that only non-composited blending elements are affected by this bug.
This CL changes behavior to match composited code path, which also matches
Firefox behavior.

BUG=673597
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
[Blink>Paint] Document element cannot always omit isolation

The previous assumption that nothing can be the backdrop of the document
element's stacking context was incorrect, because document background doesn't
paint as a part of the stacking context but as canvas backdrop instead.

Note that only non-composited blending elements are affected by this bug.
This CL changes behavior to match composited code path, which also matches
Firefox behavior.

BUG=673597
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2564423003
==========

[commit-bot: I haz the power, 2016-12-13 21:54:11]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-12-13 21:58:15]

Description was changed from

==========
[Blink>Paint] Document element cannot always omit isolation

The previous assumption that nothing can be the backdrop of the document
element's stacking context was incorrect, because document background doesn't
paint as a part of the stacking context but as canvas backdrop instead.

Note that only non-composited blending elements are affected by this bug.
This CL changes behavior to match composited code path, which also matches
Firefox behavior.

BUG=673597
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2564423003
==========

to

==========
[Blink>Paint] Document element cannot always omit isolation

The previous assumption that nothing can be the backdrop of the document
element's stacking context was incorrect, because document background doesn't
paint as a part of the stacking context but as canvas backdrop instead.

Note that only non-composited blending elements are affected by this bug.
This CL changes behavior to match composited code path, which also matches
Firefox behavior.

BUG=673597
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Committed: https://crrev.com/cf97fd35cae7ca6fae58cff6eea2f6cc59716171
Cr-Commit-Position: refs/heads/master@{#438298}
==========

[commit-bot: I haz the power, 2016-12-13 21:58:16]

Patchset 1 (id:??) landed as
https://crrev.com/cf97fd35cae7ca6fae58cff6eea2f6cc59716171
Cr-Commit-Position: refs/heads/master@{#438298}