Never move unbreakable blocks that are at the top of a column / page.

Never move unbreakable blocks that are at the top of a column / page.

That's just going to leave a column / page blank, without fitting any content
better. If the block is too tall to fit in the current column / page, it's
going to be just as too tall for the next one as well.

BUG=526098
R=jchaffraix@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201732

[Julien - ping for review, 2015-09-03 14:31:08]

The CQ bit was checked by jchaffraix@chromium.org

[Julien - ping for review, 2015-09-03 14:31:08]

lgtm

[commit-bot: I haz the power, 2015-09-03 14:31:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1318653004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1318653004/1

[commit-bot: I haz the power, 2015-09-03 17:27:15]

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

[commit-bot: I haz the power, 2015-09-03 17:27:16]

Try jobs failed on following builders:
  linux_android_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_android_r...)

[mstensho (USE GERRIT), 2015-09-03 17:29:32]

The CQ bit was checked by mstensho@opera.com

[commit-bot: I haz the power, 2015-09-03 17:29:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1318653004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1318653004/1

[commit-bot: I haz the power, 2015-09-03 18:49:28]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201732