Fix a stack overflow

pkg/analyzer/test/generated/element_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.element_test;
 
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 1691 matching lines @@
     List<DartType> normalParameters = result.normalParameterTypes;
     expect(normalParameters, hasLength(1));
     expect(normalParameters[0], normalParameterType);
     List<DartType> optionalParameters = result.optionalParameterTypes;
     expect(optionalParameters, hasLength(1));
     expect(optionalParameters[0], optionalParameterType);
     Map<String, DartType> namedParameters = result.namedParameterTypes;
     expect(namedParameters, hasLength(1));
     expect(namedParameters[namedParameterName], namedParameterType);
   }
+
+  void test_toString_recursive() {
+    FunctionElementImpl t = ElementFactory.functionElement("t");
+    FunctionElementImpl s = ElementFactory.functionElement("s");
+    t.returnType = s.type;
+    s.returnType = t.type;
+    expect(t.type.toString(), '() \u2192 () \u2192 ...');
+  }
 }
 
 @reflectiveTest
 class HtmlElementImplTest extends EngineTestCase {
   void test_equals_differentSource() {
     AnalysisContextImpl context = createAnalysisContext();
     HtmlElementImpl elementA = ElementFactory.htmlUnit(context, "indexA.html");
     HtmlElementImpl elementB = ElementFactory.htmlUnit(context, "indexB.html");
     expect(elementA == elementB, isFalse);
   }
@@ skipping 2311 matching lines @@
 
 class _FunctionTypeImplTest_isSubtypeOf_baseCase_classFunction extends
     InterfaceTypeImpl {
 
   _FunctionTypeImplTest_isSubtypeOf_baseCase_classFunction(ClassElement arg0)
       : super.con1(arg0);
 
   @override
   bool get isDartCoreFunction => true;
 }