DevTools: Allow general editing of author shadow DOM elements

DevTools: Allow general editing of author shadow DOM elements

As a drive-by, shadow DOM editing tests have been extracted into a new HTML

R=aandrey, pfeldman, vsevik
BUG=353910
NOTRY=true

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=169743

[vsevik, 2014-03-21 14:06:12]

lgtm

[apavlov, 2014-03-21 14:06:53]

The CQ bit was checked by apavlov@chromium.org

[commit-bot: I haz the power, 2014-03-21 14:06:55]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/apavlov@chromium.org/206503002/1

[commit-bot: I haz the power, 2014-03-21 15:13:55]

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

[commit-bot: I haz the power, 2014-03-21 15:13:59]

Try jobs failed on following builders:
  tryserver.blink on linux_blink_dbg

[apavlov, 2014-03-21 15:15:19]

The CQ bit was checked by apavlov@chromium.org

[commit-bot: I haz the power, 2014-03-21 15:15:25]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/apavlov@chromium.org/206503002/1

[commit-bot: I haz the power, 2014-03-21 15:15:46]

Change committed as 169743