remove ClosureWrap option and related implementation

test/checker/inferred_type_test.dart

 // Copyright (c) 2015, 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.
 
 /// Tests for type inference.
 library dev_compiler.test.inferred_type_test;
 
 import 'package:test/test.dart';
 
 import 'package:dev_compiler/src/testing.dart';
@@ skipping 1495 matching lines @@
         }
         {
           Function2<int, int> l0 = /*info:InferredTypeClosure*/(x) => x;
           Function2<int, int> l1 = /*info:InferredTypeClosure*/(x) => /*info:DynamicInvoke should be pass*/x+1;
           Function2<int, String> l2 = /*info:InferredTypeClosure should be severe:StaticTypeError*/(x) => x;
           Function2<int, String> l3 = /*info:InferredTypeClosure should be severe:StaticTypeError*/(x) => /*info:DynamicInvoke should be pass*/x.substring(3);
           Function2<String, String> l4 = /*info:InferredTypeClosure*/(x) => /*info:DynamicInvoke should be pass*/x.substring(3);
         }
       }
       '''
-    }, inferDownwards: true, wrapClosures: false);
+    }, inferDownwards: true);
   });
 }