Test runner now loads CSS and hides testArea

- serve CSS and font files properly to make sure that measurements are
  correct for the tests that need them (breadcrumb)
- added opacity to testArea to make sure nothing is visible during
  testing
Removed unused padding-right of the controls bar

Removing this doesn't affect the controls bar visually but does affect
the breadcrumb calculation when getting available width.
Breadcrumb width calculation fix

Rewrote the breadcrumb calculation to be more readable.

Breadcrumb now has a setMaxWidth() method to set the maximum allowed
width which is used to fit the breadcrumbs.

The breadcrumb width is now based on the container width, passed through
setMaxWidth() by the FileList class.