Check that window.blur() does nothing, and window.focus() only works if it is invoked from the window that opened the former. If the test passes, you should see a series of PASS messages with the last being 'All tests finished'.
This test is adopted from mozilla's tests.
PASS: The focus should not have been changed!
PASS: The focus should not have been changed!
PASS: The focus should not have been changed with URL=data:text/html,
PASS: The focus should not have been changed with URL=data:text/html,
PASS: The last opened window should be able to get focus
PASS: All tests finished