During the test, we open a new window which loads a URL, and have code to wait for that
initial browser to complete the load. For the initial browser, there is (when we open
a remote-able URL), the remoteness of that initial browser flips from non-remote to
remote. Sometimes, due to messaging / timing, the initial browser will send a message
saying that a load completed for the initial about:blank before the URL we actually
want is loaded. This causes the test to continue, and attempt to click on an element
that isn't actually on the page yet.
This modification allows us to wait for the initial browser to actually load the page
that we care about before proceeding.
I also changed some of the assertion messages to actually reflect what's being asserted,
as opposed to reflecting what is being revealed if the assertion fails.
MozReview-Commit-ID: 608SaA1nCVs
48f9109a7e