After a bit of researching, I stumbled on the idea that, perhaps, the file extensions were not migrated during the upgrade. Here’s how to do that on a Mac:

• Choose NetNeans > Preferences > Miscellaneous > Files
• Next to File Extension, choose New…
• Enter module for the File Extension.
• Select text/x-php-5 for Associated File Type (MIME).

Do the same process for .install files
Close NetBeans and reopen. The Navigator pane will now display navigation information for those file types.