On remote frame's (re)attachment, connect its widget.

On remote frame's (re)attachment, connect its widget.

A remote frame can be detached by setting its .style.display = 'none'.
  If we attach it again by setting its .style.display = '', the frame
  becomes widget/FrameView-less. This CL sets the widget of the frame.

BUG=517291
Test=With --site-per-process, navigate an <iframe> to cross site.
  See that resizing the frame works correctly, e.g.:
    document.querySelector('iframe').style.width = '400px';
  Now hide the iframe, and then make it visible:
    document.querySelector('iframe').style.display = 'none';
    document.querySelector('iframe').style.display = '';
  See that resizing the frame still works correctly. It will fail
    without this CL.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201161

[lazyboy, 2015-08-24 22:02:00]

lazyboy@chromium.org changed reviewers:
+ dcheng@chromium.org

[dcheng, 2015-08-24 23:50:15]

lgtm

[lazyboy, 2015-08-25 22:03:25]

The CQ bit was checked by lazyboy@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-25 22:03:40]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1309343002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1309343002/1

[commit-bot: I haz the power, 2015-08-25 22:08:38]

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

[commit-bot: I haz the power, 2015-08-25 22:08:39]

Dry run: This issue passed the CQ dry run.

[lazyboy, 2015-08-25 22:09:21]

The CQ bit was checked by lazyboy@chromium.org

[commit-bot: I haz the power, 2015-08-25 22:09:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1309343002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1309343002/1

[commit-bot: I haz the power, 2015-08-25 22:14:56]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201161