Fix bug in optimized byte array views on tranferable backing stores.

tests/standalone/byte_array_view_optimized_test.dart

Index: tests/standalone/byte_array_view_optimized_test.dart
===================================================================
--- tests/standalone/byte_array_view_optimized_test.dart	(revision 0)
+++ tests/standalone/byte_array_view_optimized_test.dart	(revision 0)
@@ -0,0 +1,19 @@
+// 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.
+
+// Test optimization of byte array views on external data.
+
+import "dart:scalarlist";
+
+li16(v) => v[0];
+
+main() {
+  var a = new Uint8List.transferable(2);
+  a[0] = a[1] = 0xff;
+  var b = new Int16List.view(a.asByteArray());
+  Expect.equals(-1, li16(b));
+  for (var i=0; i<10000; i++) li16(b);
+  Expect.equals(-1, li16(b));
+}
+