Add test of function types with metadata
Add test of function types with metadata

This CL extends language/metadata/metadata_location_test.dart with a
couple of extra test cases, covering the situation where the metadata
occurs on a type paramater or value parameter of a function type.

Change-Id: I9b225e8c3d72aa5ddd8893526e65ab4d1b5ab2a9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/187922
Reviewed-by: Lasse R.H. Nielsen <80295e4ef244a07779f93eaa95d582bad8e316a5@google.com>
Commit-Queue: Erik Ernst <251bb01623bfda2cd9151e339a6e783ca432874c@google.com>

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