Adds details role for blink layout tests

Adds details role for blink layout tests

Adds AX role of <details> element for blink layout tests.

BUG=N/A
R=dmazzoni

Committed: https://crrev.com/dccbae137687b9c89e5f15e2c26924719b8e7477
Cr-Commit-Position: refs/heads/master@{#323895}

[je_julie(Not used), 2015-04-05 07:20:16]

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

[je_julie(Not used), 2015-04-05 07:21:43]

Hi Dominic,

This patch adds details role for blink Layout tests.

In order to land https://codereview.chromium.org/1012383002,
this patch is required.

[dmazzoni, 2015-04-06 06:00:00]

The CQ bit was checked by dmazzoni@chromium.org

[dmazzoni, 2015-04-06 06:00:01]

lgtm

[commit-bot: I haz the power, 2015-04-06 06:00:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1066503002/1

[commit-bot: I haz the power, 2015-04-06 06:34:59]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-06 06:35:58]

Patchset 1 (id:??) landed as
https://crrev.com/dccbae137687b9c89e5f15e2c26924719b8e7477
Cr-Commit-Position: refs/heads/master@{#323895}