Add VMOptions to optimize tests that need to be (Part I).

tests/language/const_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.
 // Check const classes.
+// VMOptions=--optimization-counter-threshold=10
 
 import "package:expect/expect.dart";
 
 class AConst {
   const AConst() : b_ = 3 ;
   final int b_;
 }
 
 
 class BConst {
   const BConst();
   set foo(value) {}
   get foo { return 5; }
 
   operator [](ix) { return ix; }
-  operator []=(ix, value) {}  
+  operator []=(ix, value) {}
 }
 
 
 testMain() {
   var o = const AConst();
   Expect.equals(3, o.b_);
 
   var x = (const BConst()).foo++;
   Expect.equals(5, x);
 
   var y = (const BConst())[5]++;
   Expect.equals(5, y);
 }
 
 
 main() {
-  for (int i = 0; i < 1000; i++) {
+  for (int i = 0; i < 20; i++) {
     testMain();
   }
 }