Frontend tests should run with different window sizes

[webzwo0i]

Usually I run local browser tests with a maximized window so all toolbar icons etc fit into the upper area. On saucelabs, tests often run in smaller windows so the toolbar is wrapped at the bottom.

This can lead to failed tests. I'm not sure if it's worth running all tests with a large and not-so-large window, but it's unlikely we can identify tests that would benefit and run it only against those.

[rhansen]

I think it's best to set min-width on the iframe to something large enough to avoid the wrapping. I don't think it's useful to run all of the tests a second time with a narrow window—there should be tests that specifically test narrow windows.