Slightly restructure JSModule#open_file_path conditional
Slightly restructure JSModule#open_file_path conditional

I think that this removes some redundancy and makes the code here a
little more readable.

trotzig/import-js,lencioni/import-js,Galooshi/import-js,lencioni/import-js,lencioni/import-js,trotzig/import-js,trotzig/import-js