Fixed Move button is disabled when moving components inside conditional module
Fixed When navigating upward/backward, target parent is not set correct, resulting source to be moved in the previously selected parent
* visit() already does a wait_for_page()
* wait_for_page() already asserts on is_browser_on_page(), as it will raise a BrokenPromise after polling
* don't use is_browser_on_page() in an assertion unless you are 100% certain you're already on the page
* if an action takes you to another page, synchronize with a wait_for_page() for that new page
TNL-3296 would have been prevented with this test, adding it now to
prevent similar issues in the future. Squashed commit with doc changes,
review feedback, and run-20-times-to-ensure-not-flaky-then-unmark
all included.
Fixed the edX middleware to lazily create request
context for Mako templates, so that it is based on
any changes made to the request object.
Verified that with this fix the "Instructor" tab is
correctly hidden when a staff member is viewing
the course as a student.
