Bug 1044297 - Part 1: remove unused variables.
Bug 1044297 - Part 2: Be sure white listed apps don't run legacy test.

Apps that implement new startup events don't need to run
startup_tests test.

We check if the running app is not in the white list, if it does, we
skip the test.
Bug 1044297 - Part 3: Update mem perf tests to use new moz-app-loaded event.

After moz-app-loaded event, application has displayed content and ready
for interation. At this point, we should check for memory consumption
regressions.