Add isExpanded() API to WebAXObject.h to get aria-expanded attribute.

Add isExpanded() API to WebAXObject.h to get aria-expanded attribute.
This patch also moves isExpanded() in AXObject to AXNodeObject like
other APIs to get attribute.

BUG=98982
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=184058

[je_julie(Not used), 2014-10-20 05:22:02]

je_julie.kim@samsung.com changed reviewers:
+ dmazzoni@chromium.org, mkwst@chromium.org

[je_julie(Not used), 2014-10-20 05:30:21]

Hi Dominic and Mike,

The related CL in chromium is
https://codereview.chromium.org/665843002/
I'll update TC results there.
Could you take a look this CL first?

Thanks,

[Mike West, 2014-10-20 07:54:55]

mkwst@chromium.org changed required reviewers:
+ dmazzoni@chromium.org

[Mike West, 2014-10-20 07:54:55]

public/ LGTM, but please don't proceed with this unless Dominic agrees that it's
the right way to go.

[dmazzoni, 2014-10-20 16:36:15]

lgtm

[je_julie(Not used), 2014-10-21 08:07:11]

The CQ bit was checked by je_julie.kim@samsung.com

[commit-bot: I haz the power, 2014-10-21 08:07:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/662313003/1

[commit-bot: I haz the power, 2014-10-21 09:15:54]

Committed patchset #1 (id:1) as 184058