[heap] Filter out stale left-trimmed handles

test/mjsunit/regress/regress-620553.js

Index: test/mjsunit/regress/regress-620553.js
diff --git a/test/mjsunit/regress/regress-620553.js b/test/mjsunit/regress/regress-620553.js
new file mode 100644
index 0000000000000000000000000000000000000000..461b9bb189e559841176801fb3313d7613224c90
--- /dev/null
+++ b/test/mjsunit/regress/regress-620553.js
@@ -0,0 +1,17 @@
+// Copyright 2016 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.
+
+// Flags: --expose-gc
+
+var o0 = [];
+var o1 = [];
+var cnt = 0;
+o1.__defineGetter__(0, function() {
+  if (cnt++ > 2) return;
+  o0.shift();
+  gc();
+  o0.push(0);
+  o0.concat(o1);
+});
+o1[0];