Remove function names on function expressions.

tests/compiler/dart2js_extra/closure_capture2_test.dart

 // Copyright (c) 2012, 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.
 
 import "package:expect/expect.dart";
 
 closure0() {
   // f and g will both capture a variable named 'x'. If we use the original
   // name in the (shared) box then there will be troubles.
   var f;
   var g;
   {
     var x = 499;
-    // TODO(floitsch): remove name from functions.
-    f = fun() { return x; };
+    f = () { return x; };
     x++;
   }
   {
     var x = 42;
-    // TODO(floitsch): remove name from functions.
-    g = fun() { return x; };
+    g = () { return x; };
     x++;
   }
   Expect.equals(500, f());
   Expect.equals(43, g());
 }
 
 closure1() {
   // f captures variable $0 which once could yield to troubles with HForeign if
   // we did not mangle correctly.
   var $1 = 499;
-  // TODO(floitsch): remove name from functions.
-  var f = fun() { return $1; };
+  var f = () { return $1; };
   $1++;
   Expect.equals(500, f());
 }
 
 main() {
   closure0();
   closure1();
 }