Don't include parameter names in types, don't use Unicode arrow.

pkg/front_end/testcases/inference/block_bodied_lambdas_infer_bottom_sync.dart

 // Copyright (c) 2017, 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.
 
 /*@testedFeatures=inference*/
 library test;
 
 var /*@topType=dynamic*/ h = null;
 void foo(int f(Object _)) {}
 
 main() {
-  var /*@type=(Object x) → Null*/ f = /*@returnType=Null*/ (Object x) {
+  var /*@type=(Object) -> Null*/ f = /*@returnType=Null*/ (Object x) {
     return null;
   };
   String y = /*@promotedType=none*/ f(42);
 
   f = /*error:INVALID_CAST_FUNCTION_EXPR*/ /*@returnType=String*/ (/*@type=Object*/ x) =>
       'hello';
 
   foo(/*@returnType=Null*/ (/*@type=Object*/ x) {
     return null;
   });
   foo(/*@returnType=Null*/ (/*@type=Object*/ x) {
     throw "not implemented";
   });
 }