Don't fail the style assert in Element::rendererIsFocusable if the document is active.

Don't fail the style assert in Element::rendererIsFocusable if the document is active.

This avoids crashing in call sites that happen during document setup and shutdown
of the document. An example of the former appears to be in the attached bug.

An example of the latter is easily reproducible: load a document with hyperlinks
in it, select some text via the text finding widget (ctrl-f), then click on the 
hyperlink. The code to close the find box will call into Blink and check
if the elements are focusable. However, the elements no longer have renderers
since the document has been deactivated to prepare for navigation.

TBR=abarth@chromium.org
BUG=251163
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181497

[chrishtr, 2014-09-02 21:32:18]

chrishtr@chromium.org changed reviewers:
+ pdr@chromium.org

[chrishtr, 2014-09-02 23:33:31]

Updated to clear out layout state at the call site of Element::isFocusable. This
is what the other call sites of it do.

However, even that is not enough, since updateLayoutIgnorePendingStylesheets()
does not actually
compute style and layout for inactive documents.

[chrishtr, 2014-09-04 20:39:22]

Ping?

[pdr., 2014-09-04 21:21:37]

On 2014/09/04 20:39:22, chrishtr wrote:
> Ping?

LGTM

[pdr., 2014-09-04 21:21:39]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2014-09-04 21:22:28]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/chrishtr@chromium.org/533963002/40001

[commit-bot: I haz the power, 2014-09-04 21:32:40]

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

[commit-bot: I haz the power, 2014-09-04 21:32:41]

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

[chrishtr, 2014-09-04 21:34:41]

chrishtr@chromium.org changed reviewers:
+ abarth@chromium.org

[chrishtr, 2014-09-04 21:34:42]

Adam, need your LGTM.

[chrishtr, 2014-09-06 15:54:02]

chrishtr@chromium.org changed reviewers:
- abarth@chromium.org

[chrishtr, 2014-09-06 15:54:05]

The CQ bit was checked by chrishtr@chromium.org

[commit-bot: I haz the power, 2014-09-06 15:55:10]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/chrishtr@chromium.org/533963002/40001

[commit-bot: I haz the power, 2014-09-06 15:58:48]

Committed patchset #3 (id:40001) as 181497