Remove SILType::isExistentialMetatypeType().

Suggested by John.



Swift SVN r27864

include/swift/SIL/SILType.h

@@ -329,10 +329,6 @@ public:
   bool isClassExistentialType() const {
     return getSwiftRValueType()->isClassExistentialType();
   }
-  // Returns true if the referenced type is an existential metatype.
-  bool isExistentialMetatypeType() const {
-    return is<ExistentialMetatypeType>();
-  }
   
   /// Returns the representation used by an existential type. If the concrete
   /// type is provided, this may return a specialized representation kind that