Add failing throw test.

tests/language/throw8_test.dart

+// Copyright (c) 2011, 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 throw statement
+
+import "package:expect/expect.dart";
+
+var finallyExecutionCount = 0;
+bar() {
+  try {
+    try {
+      return 499;
+    } catch (e, st) {
+      rethrow;
+    }
+  } finally {
+    finallyExecutionCount++;
+    throw "quit finally with throw";
+  }
+}
+
+main() {
+  bool hasThrown = false;
+  try {
+    bar();
+  } catch (x) {
+    hasThrown = true;
+    Expect.equals(1, finallyExecutionCount);
+  }
+  Expect.isTrue(hasThrown);
+}