Prevent a use after free in computeBlockPreferredLogicalWidths

Prevent a use after free in computeBlockPreferredLogicalWidths

This patch fixes a use after free during preferred logical width
calculation when we have autosizing enabled. This is a speculative
local fix to see if more of these regressions pop up; the final fix
will need to address crbug.com/389648 as well.

BUG=385268
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177152

[skobes, 2014-06-27 19:16:35]

lgtm

As discussed via chat, please verify this fix on the asan trybot before
committing.

[pdr., 2014-06-27 20:09:02]

On 2014/06/27 19:16:35, skobes wrote:
> lgtm
> 
> As discussed via chat, please verify this fix on the asan trybot before
> committing.

I confirmed this locally: because this test crashed before but passes now, I had
to add the Pass expectation :)

Off to the CQ

[pdr., 2014-06-27 20:09:07]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2014-06-27 20:09:51]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/pdr@chromium.org/358163002/40001

[commit-bot: I haz the power, 2014-06-27 21:13:52]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_blink_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_dbg/builds/1...)
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/14180)

[commit-bot: I haz the power, 2014-06-27 22:20:57]

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

[commit-bot: I haz the power, 2014-06-27 22:20:58]

Try jobs failed on following builders:
  linux_blink_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_dbg/builds/1...)

[pdr., 2014-06-27 22:22:32]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2014-06-27 22:22:52]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/pdr@chromium.org/358163002/40001

[commit-bot: I haz the power, 2014-06-27 23:23:40]

Change committed as 177152