review form combobox fields should filter intelligently

[davidlhw]

When selecting an input for either course / professor using the combobox, the corresponding combobox should filter with relevant values of professors teaching the selected course or course taught by selected professors

eg:

given prof X,Y,Z teaches course A
when user selects course A
should only see prof X,Y,Z on the prof combobox dropdown

given prof X teaches course A,B and prof Y teaches course A,C
when user selects prof Y
should only see course A,C in the course combobox dropdown