Bug 839746: added tests for tabs/utils getTabs, added tests for panel/window getWindow, and page-mods in global pb
(cherry picked from commit 529de8625b6d9d3ea6b2051c34c8291f12ef4453)

Conflicts:

	test/test-page-mod.js
	test/test-panel.js
Merge pull request #892 from erikvold/839746-4-master

Bug 839746: added tests for tabs/utils and panel r=@gozala