[ic] Don't check full prototype chain if name is a private symbol.

test/mjsunit/regress/regress-crbug-664802.js

Index: test/mjsunit/regress/regress-crbug-664802.js
diff --git a/test/mjsunit/regress/regress-crbug-664802.js b/test/mjsunit/regress/regress-crbug-664802.js
new file mode 100644
index 0000000000000000000000000000000000000000..3395f4c6763a6160d96495fda8b575912c1397b0
--- /dev/null
+++ b/test/mjsunit/regress/regress-crbug-664802.js
@@ -0,0 +1,10 @@
+// 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.
+
+var o = {};
+o.__proto__ = new Proxy({}, {});
+
+var m = new Map();
+m.set({});
+m.set(o);