Fix a bug with store-to-load forwarding for typed arrays.

tests/language/int_array_load_elimination_test.dart

+// Copyright (c) 2012, 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.
+//
+// Test correct load elimination for scalar lists.
+
+import 'dart:scalarlist';
+
+void testUint16() {
+  Int16List intArray = new Uint16List(1);
+  intArray[0] = -1;
+  var x = intArray[0];
+  Expect.equals(65535, x);
+}
+
+main() {
+  for (int i = 0; i < 2000; i++) {
+    testUint16();
+  }
+}