Bugzilla

+++ This bug was initially created as a clone of Bug #1587971 +++

Plain mochitests run in a content process, so when one does a `window.open("http://example.com/")`, that ends up in a different content process under fission.

Which means this test needs to inspect internal state of another content process, which is not easy from a plain mochitest.  Solutions are changing this to a browser mochitest, an xpcshell test, or just opening the second tab from the same origin (mochi.test) to keep it in the same process.

Alternatives are mostly equivalent, but third is easiest/smallest change.

HSTS upgrade means changing the origin of the tab, which means going through a process switch with fission, which leaves us with intermediate about:blank updates inbetween that we need to ignore.