go/types, types2: delete _TypeSet.includes - not used (cleanup)

Change-Id: Ia324c6185e36efd4ea7dc92d7c2233fec8f5a55f
Reviewed-on: https://go-review.googlesource.com/c/go/+/381494
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

src/cmd/compile/internal/types2/typeset.go

@@ -107,11 +107,6 @@ func (s *_TypeSet) hasTerms() bool { return !s.terms.isEmpty() && !s.terms.isAll
 // singleType returns the single type in s if there is exactly one; otherwise the result is nil.
 func (s *_TypeSet) singleType() Type { return s.terms.singleType() }
 
-// includes reports whether t ∈ s.
-// TODO(gri) This function is not used anywhere anymore. Remove once we
-//           are clear that we don't need it elsewhere in the future.
-func (s *_TypeSet) includes(t Type) bool { return s.terms.includes(t) }
-
 // subsetOf reports whether s1 ⊆ s2.
 func (s1 *_TypeSet) subsetOf(s2 *_TypeSet) bool { return s1.terms.subsetOf(s2.terms) }
 

src/go/types/typeset.go

@@ -105,11 +105,6 @@ func (s *_TypeSet) hasTerms() bool { return !s.terms.isEmpty() && !s.terms.isAll
 // singleType returns the single type in s if there is exactly one; otherwise the result is nil.
 func (s *_TypeSet) singleType() Type { return s.terms.singleType() }
 
-// includes reports whether t ∈ s.
-// TODO(gri) This function is not used anywhere anymore. Remove once we
-//           are clear that we don't need it elsewhere in the future.
-func (s *_TypeSet) includes(t Type) bool { return s.terms.includes(t) }
-
 // subsetOf reports whether s1 ⊆ s2.
 func (s1 *_TypeSet) subsetOf(s2 *_TypeSet) bool { return s1.terms.subsetOf(s2.terms) }