[display] too much stuff (2)

Toplevel completion includes .hx files that are not part of the classpath, such as these unit test classes in a Flixel project (where flixel is installed from GitHub to actually include these files):


This didn't happen with rc.3. Probably this means that `readClassPaths` now explores things it shouldn't / didn't used to?

Start with the Toplevel completion path and inspect how readClassPaths handles .hx files compared with rc.3. Reproduce the Flixel project case, where unit-test classes outside the classpath appear in completion, and use that behavior to define the fix. Done means unrelated non-classpath files no longer appear in Toplevel completion.

Written by the indexing model from the issue text.