Now that we have generic defaults (:tada:), we should consider making all type parameters have an implicit any default. An unspecified uninferred type parameter would have type any and trigger a warning under noImplicitAny.

Benefits:

• We'll need to do this in Salsa anyway
• Improves JS migration story for codebases which inherit from generic base classes

Drawbacks:

• There may exist people who run with noImplicitAny off but still want to enforce type parameters to be provided?