Bug 899630 - Intermittent Jetpack tests/test-tabs.testTabsEvent_onCloseWindow

Removing the use of a special window closer to trigger end of test
Merge branch 'master' of git://github.com/mozilla/addon-sdk into 899630v2

Conflicts:
	test/tabs/test-firefox-tabs.js
Merge pull request #1174 from erikvold/899630v2

Bug 899630 - Intermittent Jetpack tests/test-tabs.testTabsEvent_onCloseWindow r=@ZER0