Don't delete a flow thread just because it becomes childless.

Don't delete a flow thread just because it becomes childless.

This is a revert of overzealous cleanup done in
https://codereview.chromium.org/769093002
Let's update the comment instead. A flow thread needs to exist as long
as its parent multicol/paged container exists. A flowthread's lifespan
does not depend on its children.

R=jchaffraix@chromium.org
BUG=438573
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=186484

[Julien - ping for review, 2014-12-03 23:05:00]

lgtm

https://codereview.chromium.org/776653003/diff/1/LayoutTests/fast/multicol/re...
File LayoutTests/fast/multicol/remove-all-children.html (right):

https://codereview.chromium.org/776653003/diff/1/LayoutTests/fast/multicol/re...
LayoutTests/fast/multicol/remove-all-children.html:13: <p>PASS if no crash</p>
Let's add a description of what the test is testing.

https://codereview.chromium.org/776653003/diff/1/Source/core/rendering/Render...
File Source/core/rendering/RenderObject.cpp (right):

https://codereview.chromium.org/776653003/diff/1/Source/core/rendering/Render...
Source/core/rendering/RenderObject.cpp:2405: if
(destroyRootParent->isRenderFlowThread() ||
destroyRootParent->isAnonymousColumnSpanBlock())
I would keep the 2 conditions separated as it would make it more obvious which
comments refers to what.

[mstensho (USE GERRIT), 2014-12-04 06:57:06]

https://codereview.chromium.org/776653003/diff/1/LayoutTests/fast/multicol/re...
File LayoutTests/fast/multicol/remove-all-children.html (right):

https://codereview.chromium.org/776653003/diff/1/LayoutTests/fast/multicol/re...
LayoutTests/fast/multicol/remove-all-children.html:13: <p>PASS if no crash</p>
On 2014/12/03 23:05:00, Julien Chaffraix - PST wrote:
> Let's add a description of what the test is testing.

Done.

https://codereview.chromium.org/776653003/diff/1/Source/core/rendering/Render...
File Source/core/rendering/RenderObject.cpp (right):

https://codereview.chromium.org/776653003/diff/1/Source/core/rendering/Render...
Source/core/rendering/RenderObject.cpp:2405: if
(destroyRootParent->isRenderFlowThread() ||
destroyRootParent->isAnonymousColumnSpanBlock())
On 2014/12/03 23:05:00, Julien Chaffraix - PST wrote:
> I would keep the 2 conditions separated as it would make it more obvious which
> comments refers to what.

Done.

[mstensho (USE GERRIT), 2014-12-04 06:57:28]

The CQ bit was checked by mstensho@opera.com

[commit-bot: I haz the power, 2014-12-04 06:58:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/776653003/40001

[commit-bot: I haz the power, 2014-12-04 08:03:24]

Committed patchset #3 (id:40001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=186484