More tests updated to optimize code (Part 2).

tests/language/issue7513_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.
+// VMOptions=--optimization-counter-threshold=10 --no-use-osr
 
 import "package:expect/expect.dart";
 
 // Regression test for issue 7513.
 
 foo(a, b) {
   b[0] = 0.1;
   return a * b[0];
 }
 
 main() {
   var a = 0.1;
   var b = [0.1];
-  for (var i = 0; i < 10000; i++) {
+  for (var i = 0; i < 20; i++) {
     foo(a, b);
   }
   Expect.approxEquals(0.01, foo(a, b));
 }