[New Multicolumn] Guard against zero or negative space shortage.

[New Multicolumn] Guard against zero or negative space shortage.

We need positive values in order to get anywhere when stretching columns
in order to balance them, and we may get called with zero or negative
values when there's zero-height content at column boundaries, or when we
set an early break in order to honor widows in the next column.

BUG=369985
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=174088

[rune, 2014-05-06 09:00:06]

non-owner rslgtm with nits.

The code change sounds reasonable, but I don't know enough about breaking
columns to be certain.

Note: I find it easier to review new files when uploaded with --no-find-copies.

https://codereview.chromium.org/263203003/diff/1/LayoutTests/fast/multicol/wi...
File LayoutTests/fast/multicol/widows.html (right):

https://codereview.chromium.org/263203003/diff/1/LayoutTests/fast/multicol/wi...
LayoutTests/fast/multicol/widows.html:5: testRunner.dumpAsText();

Unnecessary.

https://codereview.chromium.org/263203003/diff/1/LayoutTests/fast/multicol/wi...
File LayoutTests/fast/multicol/widows2.html (right):

https://codereview.chromium.org/263203003/diff/1/LayoutTests/fast/multicol/wi...
LayoutTests/fast/multicol/widows2.html:5: testRunner.dumpAsText();

This is unnecessary as it's already called from js-test.js.

[mstensho (USE GERRIT), 2014-05-06 09:17:32]

On 2014/05/06 09:00:06, rune wrote:
> Note: I find it easier to review new files when uploaded with
--no-find-copies.

In this case it found the right copies, though. Files in compare-with-old-impl/
are temporary anyway.

[mstensho (USE GERRIT), 2014-05-06 09:17:39]

https://codereview.chromium.org/263203003/diff/1/LayoutTests/fast/multicol/wi...
File LayoutTests/fast/multicol/widows.html (right):

https://codereview.chromium.org/263203003/diff/1/LayoutTests/fast/multicol/wi...
LayoutTests/fast/multicol/widows.html:5: testRunner.dumpAsText();
On 2014/05/06 09:00:06, rune wrote:
> 
> Unnecessary.

Done.

https://codereview.chromium.org/263203003/diff/1/LayoutTests/fast/multicol/wi...
File LayoutTests/fast/multicol/widows2.html (right):

https://codereview.chromium.org/263203003/diff/1/LayoutTests/fast/multicol/wi...
LayoutTests/fast/multicol/widows2.html:5: testRunner.dumpAsText();
On 2014/05/06 09:00:06, rune wrote:
> 
> This is unnecessary as it's already called from js-test.js.

Done.

[mstensho (USE GERRIT), 2014-05-06 09:18:08]

Code review.

[Julien - ping for review, 2014-05-07 01:12:07]

lgtm

https://codereview.chromium.org/263203003/diff/20001/LayoutTests/fast/multico...
File LayoutTests/fast/multicol/widows2.html (right):

https://codereview.chromium.org/263203003/diff/20001/LayoutTests/fast/multico...
LayoutTests/fast/multicol/widows2.html:6: </script>
Description of the test?

https://codereview.chromium.org/263203003/diff/20001/LayoutTests/fast/multico...
LayoutTests/fast/multicol/widows2.html:8: <div id="mc" style="-webkit-columns:3;
columns:3; -webkit-column-rule:solid; line-height:50px;">
Do we need to use the prefixed properties?

https://codereview.chromium.org/263203003/diff/20001/LayoutTests/fast/multico...
LayoutTests/fast/multicol/widows2.html:9: <div style="orphans:1; widows:5;">
It seems like we don't use the orphan rule so could it be removed?

[mstensho (USE GERRIT), 2014-05-07 05:52:32]

The CQ bit was checked by mstensho@opera.com

[commit-bot: I haz the power, 2014-05-07 05:53:40]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mstensho@opera.com/263203003/50001

[commit-bot: I haz the power, 2014-05-07 07:03:45]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  win_blink_rel on tryserver.blink

[mstensho (USE GERRIT), 2014-05-07 07:33:39]

https://codereview.chromium.org/263203003/diff/20001/LayoutTests/fast/multico...
File LayoutTests/fast/multicol/widows2.html (right):

https://codereview.chromium.org/263203003/diff/20001/LayoutTests/fast/multico...
LayoutTests/fast/multicol/widows2.html:6: </script>
On 2014/05/07 01:12:07, Julien Chaffraix - PST wrote:
> Description of the test?

Done.

https://codereview.chromium.org/263203003/diff/20001/LayoutTests/fast/multico...
LayoutTests/fast/multicol/widows2.html:8: <div id="mc" style="-webkit-columns:3;
columns:3; -webkit-column-rule:solid; line-height:50px;">
On 2014/05/07 01:12:07, Julien Chaffraix - PST wrote:
> Do we need to use the prefixed properties?

Yes, that's the only thing Blink supports. Should remove prefixes once this new 
multicol implementation is enabled by default.

https://codereview.chromium.org/263203003/diff/20001/LayoutTests/fast/multico...
LayoutTests/fast/multicol/widows2.html:9: <div style="orphans:1; widows:5;">
On 2014/05/07 01:12:07, Julien Chaffraix - PST wrote:
> It seems like we don't use the orphan rule so could it be removed?

According to the spec (CSS 2.1), the initial value for 'orphans' is '2', which I
don't want. Not that Blink actually implements this exactly like the spec says,
but that's a different issue.

[commit-bot: I haz the power, 2014-05-07 08:13:45]

FYI, CQ is re-trying this CL (attempt #2).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  linux_blink_dbg on tryserver.blink
  linux_blink_rel on tryserver.blink
  mac_blink_rel on tryserver.blink
  win_blink_rel on tryserver.blink

[commit-bot: I haz the power, 2014-05-07 08:47:16]

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

[commit-bot: I haz the power, 2014-05-07 08:47:16]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink
  mac_blink_rel on tryserver.blink

[mstensho (USE GERRIT), 2014-05-07 09:13:59]

The CQ bit was checked by mstensho@opera.com

[commit-bot: I haz the power, 2014-05-07 09:15:13]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mstensho@opera.com/263203003/70001

[commit-bot: I haz the power, 2014-05-07 10:26:36]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  win_blink_rel on tryserver.blink

[mstensho (USE GERRIT), 2014-05-07 11:28:37]

The CQ bit was unchecked by mstensho@opera.com

[mstensho (USE GERRIT), 2014-05-07 11:44:36]

One of the tests crashes (assertion failure). Need to land a patch (not uploaded
yet) that cleans up layoutColumns() & friends first.

[mstensho (USE GERRIT), 2014-05-15 13:50:19]

The CQ bit was checked by mstensho@opera.com

[commit-bot: I haz the power, 2014-05-15 13:50:29]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mstensho@opera.com/263203003/110001

[commit-bot: I haz the power, 2014-05-15 15:02:07]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  mac_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/6779)

[commit-bot: I haz the power, 2014-05-15 15:44:44]

Change committed as 174088