||This test checks that the SidebarFocused event doesn't fire in adopted
windows when the sidebar gets opened during window opening, to make sure
that sidebars don't steal focus from the page in this case (Bug 1394207).
There's another case not covered here that has the same expected behavior -
during the initial browser startup - but it would be hard to do with a mochitest.
||Any copyright is dedicated to the Public Domain.