Need to roll back the multicol machinery state when re-laying out a block child.

Need to roll back the multicol machinery state when re-laying out a block child.

If a block child contains a column spanner, and we need to re-lay it out
because the initial logical top estimate turned out to be wrong, we need to
roll back to the first column set that "contains" the block child.

Otherwise, LayoutMultiColumnFlowThread::columnSetAtBlockOffset() may return the
wrong column set.

BUG=633411
Committed: https://crrev.com/bd5569ad477b5137724faa937a8bc894f8335f07
Cr-Commit-Position: refs/heads/master@{#411352}

[mstensho (USE GERRIT), 2016-08-11 10:38:23]

The CQ bit was checked by mstensho@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2016-08-11 10:38:40]

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

[mstensho (USE GERRIT), 2016-08-11 11:51:45]

mstensho@opera.com changed reviewers:
+ eae@chromium.org

[mstensho (USE GERRIT), 2016-08-11 11:51:45]

Perfect image of "column-span:all":

http://london-efl.org/spanner.jpg

[commit-bot: I haz the power, 2016-08-11 13:50:54]

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

[commit-bot: I haz the power, 2016-08-11 13:50:56]

Dry run: Try jobs failed on following builders:
  win_chromium_rel_ng on master.tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[eae, 2016-08-11 14:14:01]

LGTM

http://i150.photobucket.com/albums/s90/robinwhitman/epw_2008/chaplin-gears.jpg

[mstensho (USE GERRIT), 2016-08-11 14:36:01]

The CQ bit was checked by mstensho@opera.com

[commit-bot: I haz the power, 2016-08-11 14:36:22]

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, 2016-08-11 16:32:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-11 16:35:14]

Description was changed from

==========
Need to roll back the multicol machinery state when re-laying out a block child.

If a block child contains a column spanner, and we need to re-lay it out
because the initial logical top estimate turned out to be wrong, we need to
roll back to the first column set that "contains" the block child.

Otherwise, LayoutMultiColumnFlowThread::columnSetAtBlockOffset() may return the
wrong column set.

BUG=633411
==========

to

==========
Need to roll back the multicol machinery state when re-laying out a block child.

If a block child contains a column spanner, and we need to re-lay it out
because the initial logical top estimate turned out to be wrong, we need to
roll back to the first column set that "contains" the block child.

Otherwise, LayoutMultiColumnFlowThread::columnSetAtBlockOffset() may return the
wrong column set.

BUG=633411

Committed: https://crrev.com/bd5569ad477b5137724faa937a8bc894f8335f07
Cr-Commit-Position: refs/heads/master@{#411352}
==========

[commit-bot: I haz the power, 2016-08-11 16:35:15]

Patchset 1 (id:??) landed as
https://crrev.com/bd5569ad477b5137724faa937a8bc894f8335f07
Cr-Commit-Position: refs/heads/master@{#411352}