Tests that browser.Target.setAutoAttach() attaches to pages opened by click on noopener link.

Clicking on body > a[rel]
Attached to new window
Resumed
New window content:
HTTP_USER_AGENT: Overridden value


Clicking on body > a:not([rel])
Attached to new window
Resumed
New window content:
HTTP_USER_AGENT: Overridden value