Don't crash in V8Window::openMethodCustom when called on RemoteDOMWindow.

Don't crash in V8Window::openMethodCustom when called on RemoteDOMWindow.

Currently, openMethodCustom assumes it's called on a LocalDOMWindow,
which may not be true in --site-per-process mode.  This CL moves the
cast to LocalDOMWindow to be done after the BindingSecurity check,
which should throw exceptions when called on RemoteDOMWindows (since
those are always cross-origin).

BUG=501414, 477150
TEST=http/tests/security/xss-exception.html with --site-per-process

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197295

[alexmos, 2015-06-17 21:58:01]

alexmos@chromium.org changed reviewers:
+ haraken@chromium.org

[alexmos, 2015-06-17 22:00:29]

haraken@: PTAL.

[haraken, 2015-06-17 22:02:03]

LGTM

[alexmos, 2015-06-17 22:06:40]

The CQ bit was checked by alexmos@chromium.org

[commit-bot: I haz the power, 2015-06-17 22:07:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1194563003/1

[commit-bot: I haz the power, 2015-06-17 23:31:42]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197295