Invalidate the global property cell when converting from data to accessor.

test/mjsunit/regress/convert-global-data-to-accessor.js

Index: test/mjsunit/regress/convert-global-data-to-accessor.js
diff --git a/test/mjsunit/regress/convert-global-data-to-accessor.js b/test/mjsunit/regress/convert-global-data-to-accessor.js
new file mode 100644
index 0000000000000000000000000000000000000000..976470935d18efe482dd3eeb6710e3ebf0ffcc7e
--- /dev/null
+++ b/test/mjsunit/regress/convert-global-data-to-accessor.js
@@ -0,0 +1,15 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+function f(o) {
+  return o.x;
+}
+this.x = 100;
+f(this);
+f(this);
+f(this);
+
+Object.defineProperty(this, 'x', { get: function() { return 10; }});
+assertEquals(10, this.x);
+assertEquals(10, f(this));