More tests updated to optimize code (Part 2).

tests/language/exception_in_increment_test.dart

Index: tests/language/exception_in_increment_test.dart
===================================================================
--- tests/language/exception_in_increment_test.dart	(revision 24922)
+++ tests/language/exception_in_increment_test.dart	(working copy)
@@ -3,11 +3,12 @@
 // BSD-style license that can be found in the LICENSE file.
 // Test throws exception in the middle of the increment operation, the setter
 // part of the instance field increment never completes.
+// VMOptions=--optimization-counter-threshold=10
 
 main() {
   var a = new A();
   a.field = new A();
-  for (int i = 0; i < 4000; i++) {
+  for (int i = 0; i < 20; i++) {
     try {
       a.foo(i);
     } catch (e) {