Exact match on term types when determining whether doc or test.

[ChrisPenner]

Overview

Fixes #4407

Don't do subtype matching for docs and terms or we'll match fully polymorphic terms.

Docs and types don't have type variables anyways, so we can do a full equality check.

Implementation notes

Switch to an isEqual rather than isSubtype check for whether terms are docs or tests.

Testing

• Tested locally

[aryairani]

Sweet!