Fix bug #10089 ([CEF 2171] Cannot reopen Jasmine test window after closing it) --
We were previously relying on accessing window.location throwing an exception
to tell that the test window was closed. In newer Chrome, it's simply stubbed
out instead.

Check window.closed instead, which is a much more standard way to get this info.
Merge pull request #10098 from adobe/pflynn/testrunner-window-reopen

Fix bug #10089 ([CEF 2171] Cannot reopen Jasmine test window after closing it)