Gracefully handle unruly children detaching our frame and client.

Gracefully handle unruly children detaching our frame and client.

When committing the load of a new document to a frame, any current
document is first detached, along with the child frames. Should these
children trigger the detachment of the frame getting a new document,
by updating the frame tree above us, simply abandon the frame loading
operation.

R=japhet,dcheng
BUG=476837
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=194679

[sof, 2015-04-29 19:44:40]

sigbjornf@opera.com changed reviewers:
+ dcheng@chromium.org, japhet@chromium.org

[sof, 2015-04-29 19:44:41]

please take a look.

[Nate Chapin, 2015-04-29 19:47:53]

lgtm

[dcheng, 2015-04-29 20:00:09]

lgtm

[sof, 2015-04-29 20:56:49]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-04-29 20:57:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1116763002/1

[commit-bot: I haz the power, 2015-04-29 23:47:00]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=194679