Tests for the PPA related javascript

[Celso Providelo]

There are already few untested javascript features in the PPA area.

 1. Repository-size and expandable-package-row dynamically loaded section;
 2. Build-counters periodic updates.
 3. The related PPAs slider on the DistributionSourcePackage page need a simple integration test

Independent of the fact that some of the code will eventually be moved to lazr-js, it would be much easier to land changes and improvements if we have integration tests in place.