[FastTextAutosizer] Do not inflate blocks with no children

[FastTextAutosizer] Do not inflate blocks with no children

This patch fixes a crash on empty documents where a cluster would not
get created and we would crash during inflation. I've changed
beginLayout to only call inflate when a block has children, and
refactored endLayout similarly.

BUG=348458
NOTRY=true

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=168352

[skobes, 2014-03-03 21:27:33]

lgtm

[pdr., 2014-03-03 21:30:47]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2014-03-03 21:30:58]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/pdr@chromium.org/182443004/1

[commit-bot: I haz the power, 2014-03-03 23:21:54]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/pdr@chromium.org/182443004/1

[pdr., 2014-03-04 02:58:34]

On 2014/03/03 23:21:54, I haz the power (commit-bot) wrote:
> CQ is trying da patch. Follow status at
> https://chromium-status.appspot.com/cq/pdr%40chromium.org/182443004/1

win_layout has been wedged for 3.5 hours. NOTRY=true'ing

[pdr., 2014-03-04 02:58:39]

The CQ bit was unchecked by pdr@chromium.org

[pdr., 2014-03-04 02:58:45]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2014-03-04 02:58:56]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/pdr@chromium.org/182443004/1

[commit-bot: I haz the power, 2014-03-04 03:09:43]

Change committed as 168352