Add regression test to close #52883

Author: AnthonyLatsis

test/decl/protocol/protocol_with_superclass.swift

@@ -351,3 +351,11 @@ func usesProtoRefinesClass2<T : ProtoRefinesClassComposition>(_ t: T) {
   t.genericMethod((1, 2))
   let _: BaseProto = t
 }
+
+class SR10483_C: SR10483_P {}
+protocol SR10483_P: SR10483_C {
+  func foo()
+}
+extension SR10483_P {
+  func foo() {}
+}