Adding a step to wait for loaded modules. This was manily taken from
the Popups-extension browser test, but with a fixed chain for the
results.
Let's hope we do not need to pause with this.
See as well I274bdee0b3c39c418a2b61881d56f89889c53485
Bug: T220318
Change-Id: I5bdc1951a23a51e9a4deea69af2bfc96843f5a1d
This also includes putting the backling tests in their
own file due to the common setup needed.
Bug: T205271
Change-Id: Ica98c31bf0fddde9eb80f9c53b3dc089cb60e30c