Start refactor of ComboBox/FilteringSelect tests.
Start refactor of ComboBox/FilteringSelect tests.

They were testing the same functionality on many combobox instances, thus taking much too long to run
and yet without testing many features, such as the filtering of choices the drop down list based on
what the user has typed so far.

Removed redundant tests and added TODO's for missing tests.

Refs #7681

git-svn-id: 674a2d6b1e32e53f607eb824547723f32280967e@17041 560b804f-0ae3-0310-86f3-f6aa0a117693

redaktor/deliteful