Fix bug with captured parameters and optimized try-catch.

tests/language/vm/optimized_await_regress_test.dart

+// Copyright (c) 2014, 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=--enable_async --optimization-counter-threshold=10
+
+// This tests that captured parameters (by the async-closure) are
+// correctly treated in try-catch generated in the async function.
+// They must be skipped when generating sync-code in the optimized
+// try-block.
+
+import 'package:expect/expect.dart';
+
+import 'dart:async';
+
+check(value) {
+  try {
+  } finally {
+    return value;
+  }
+}
+
+fail() {
+  try {
+    Expect.isTrue(false);
+  } finally { }
+}
+
+foo(i) async {
+  var k = await 77;
+  var a = "abc${k}";
+  if (a != "abc77") fail();
+  return k;
+}
+
+
+main() {
+  for (int i = 0; i < 20; i++) {
+    foo(i).then((value) => Expect.equals(77, value));
+  }
+}