Correctly resolve active descendant when describing change events.

Correctly resolve active descendant when describing change events.

BUG=
TEST=chromevox_tests (and manualy on Sheets format panel).

Committed: https://crrev.com/7556b6b4ac505094335800f2f1bfea13d43e566d
Cr-Commit-Position: refs/heads/master@{#311360}

[David Tseng, 2015-01-13 21:37:34]

dtseng@chromium.org changed reviewers:
+ dmazzoni@chromium.org

[dmazzoni, 2015-01-13 21:45:19]

The CQ bit was checked by dmazzoni@chromium.org

[dmazzoni, 2015-01-13 21:45:19]

lgtm

[commit-bot: I haz the power, 2015-01-13 21:46:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/841453005/1

[commit-bot: I haz the power, 2015-01-13 21:46:24]

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

[commit-bot: I haz the power, 2015-01-13 21:46:25]

CLs for remote refs other than refs/pending/heads/master must contain NOTRY=true
in order for the CQ to process them

[David Tseng, 2015-01-13 22:36:49]

The CQ bit was checked by dtseng@chromium.org

[commit-bot: I haz the power, 2015-01-13 22:37:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/841453005/20001

[commit-bot: I haz the power, 2015-01-13 23:05:23]

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

[commit-bot: I haz the power, 2015-01-13 23:05:24]

Try jobs failed on following builders:
  ios_dbg_simulator on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_dbg_simulator...)

[David Tseng, 2015-01-13 23:13:15]

The CQ bit was checked by dtseng@chromium.org

[commit-bot: I haz the power, 2015-01-13 23:14:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/841453005/20001

[commit-bot: I haz the power, 2015-01-13 23:32:08]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-13 23:33:22]

Patchset 2 (id:??) landed as
https://crrev.com/7556b6b4ac505094335800f2f1bfea13d43e566d
Cr-Commit-Position: refs/heads/master@{#311360}