Support verified heap pointer writes on ia32.

tests/standalone/verified_mem_test.dart

Index: tests/standalone/verified_mem_test.dart
===================================================================
--- tests/standalone/verified_mem_test.dart	(revision 0)
+++ tests/standalone/verified_mem_test.dart	(working copy)
@@ -0,0 +1,17 @@
+// 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.
+//
+// Test write barrier verification mode.
+// VMOptions=--verified_mem --verify_before_gc --verify_after_gc
+
+var a = [];
+
+void main() {
+  for (int i = 0; i < 123; ++i) {
+    a.add(new List(12345));
+  }
+  for (int i = 0; i < 12345; ++i) {
+    a[0] = new List(100000);
+  }
+}