anchor.diff:        expect(element.returnType, returnType);
       } else if (isNullExpectedReturnTypeConsideredDynamic) {
         expect(element.returnType, 'dynamic');
  -    } else {
  -      expect(element.returnType, isNull);
       }
       assertHasNoParameterInfo(cs);
       return cs;
  
positive.code:       expect(cs.returnType, returnType);
      } else if (isNullExpectedReturnTypeConsideredDynamic) {
        expect(cs.returnType, 'dynamic');
      } else {
        expect(cs.returnType, isNull);
      }
      protocol.Element element = cs.element;
      expect(element, isNotNull);
  
negative.code:       expect(element.returnType, returnType);
      } else if (isNullExpectedReturnTypeConsideredDynamic) {
        expect(element.returnType, 'dynamic');
      }
      assertHasParameterInfo(cs);
      return cs;
  