Fix braino in SSA optimizer and add a test for it.

tests/language/null_no_such_method_test.dart

Index: tests/language/null_no_such_method_test.dart
===================================================================
--- tests/language/null_no_such_method_test.dart	(revision 0)
+++ tests/language/null_no_such_method_test.dart	(revision 0)
@@ -0,0 +1,11 @@
+// Copyright (c) 2013, 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.
+
+var array = [1];
+
+main() {
+  Expect.throws(() => -null, (e) => e is NoSuchMethodError);
+  // Make sure we have an untyped call to operator-.
+  print(-array[0]);
+}