VM: Make optimized try-catch work in DBC.

tests/language/try_catch_optimized5_test.dart

 // Copyright (c) 2016, 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.
 // Dart test program for testing try/catch statement without any exceptions
 // being thrown.
 // VMOptions=--optimization-counter-threshold=100 --no-background-compilation --enable-inlining-annotations
 
-// Test local variables updated inside try-catch.
+// Test optional parameters updated inside try-catch
 
 import "package:expect/expect.dart";
 
 const noInline = "NeverInline";
 
 @noInline
 m1(int b) {
   if (b == 1) throw 123;
 }
 
 
 @noInline
 m2(int b) {
   if (b == 2) throw 456;
 }
 
 
 @noInline
-test(b) {
-  var state = 0;
+test1(int b, [int state = 0]) {
   try {
     state++;
     m1(b);
     state++;
     m2(b);
     state++;
   } on dynamic catch (e, s) {
     if (b == 1 && state != 1) throw "fail1";
     if (b == 2 && state != 2) throw "fail2";
     if (b == 3 && state != 3) throw "fail3";
+    if (s is! StackTrace) throw "fail4";
+    return e;
+  }
+  return "no throw";
+}
+
+@noInline
+test2(int b, [int state]) {
+  state = 0;
+  try {
+    state++;
+    m1(b);
+    state++;
+    m2(b);
+    state++;
+  } on dynamic catch (e, s) {
+    if (b == 1 && state != 1) throw "fail1";
+    if (b == 2 && state != 2) throw "fail2";
+    if (b == 3 && state != 3) throw "fail3";
+    if (s is! StackTrace) throw "fail4";
     return e;
   } 
   return "no throw";
 }
 
 main() {
   for (var i=0; i<300; i++) {
-    Expect.equals("no throw", test(0));
+    Expect.equals("no throw", test1(0));
   }
-  Expect.equals("no throw", test(0));
-  Expect.equals(123, test(1));
-  Expect.equals(456, test(2));
+  Expect.equals("no throw", test1(0));
+  Expect.equals(123, test1(1));
+  Expect.equals(456, test1(2));
+
+  for (var i=0; i<300; i++) {
+    Expect.equals("no throw", test2(0));
+  }
+  Expect.equals("no throw", test2(0));
+  Expect.equals(123, test2(1));
+  Expect.equals(456, test2(2));
 }