Switch back to sys frame in test_call_contact
r=jgriffin in IRC; disabling this test due to bug 840612.

Bug 840612 - Connection to Mozilla Guest wi-fi looks successful, but actually isn't
Disabling due to bug 833764 - target is null after tapping on cards view; r=jgriffin in IRC
Merge pull request #383 from zacc/switch_before_frame_lost

Switch back to sys frame in test_call_contact
Merge remote-tracking branch 'mozilla/master' into gallery_flick
code review update