Map ROLE_SYSTEM_GROUPING to AX role for figure

Map ROLE_SYSTEM_GROUPING to AX role for figure
The spec says that ROLE_SYSTEM_GROUPING should be mapped for figure.
http://rawgit.com/w3c/aria/master/html-aam/html-aam.html#el-figure

BUG=282035
Committed: https://crrev.com/4f2ae4ffd6d2485bc868f0b658c08f7cbb3d2e28
Cr-Commit-Position: refs/heads/master@{#303496}

[je_julie(Not used), 2014-11-10 14:47:15]

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

[je_julie(Not used), 2014-11-10 14:52:03]

Hi Dominic,

The spec was updated recently.
http://rawgit.com/w3c/aria/master/html-aam/html-aam.html#el-figure

So, I updated code for figure role and test results.
I'll keep updating code to meet the requirement of this spec.
PTAL.

[dmazzoni, 2014-11-10 17:09:47]

The CQ bit was checked by dmazzoni@chromium.org

[dmazzoni, 2014-11-10 17:09:47]

lgtm

[commit-bot: I haz the power, 2014-11-10 17:11:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/711003003/1

[commit-bot: I haz the power, 2014-11-10 18:18:29]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-10 18:19:12]

Patchset 1 (id:??) landed as
https://crrev.com/4f2ae4ffd6d2485bc868f0b658c08f7cbb3d2e28
Cr-Commit-Position: refs/heads/master@{#303496}