Workaround for "xhr.restore" failures.

STUD-1040

@wedaly and @singingwolfboy Please review.

Add ?w=1 to review (especially for course_info_spec).

This also enables the assets_spec test-- for some reason, the special "squire" test runner was commented out.

Note that this does not fix the underlying problem of one suite becoming the "parent" of another. However, it prevents multiple cleanup operations from happening. I will write extensive notes in the Jira ticket itself.