Merged r20233 into trunk branch.

test/mjsunit/es6/regress/regress-2034.js

 // Copyright 2012 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
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 //       contributors may be used to endorse or promote products derived
 //       from this software without specific prior written permission.
 //
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+// Flags: --harmony-weak-collections
+
 var key = {};
 var map = new WeakMap;
 Object.preventExtensions(key);
 
 // Try querying using frozen key.
 assertFalse(map.has(key));
 assertSame(undefined, map.get(key));
 
 // Try adding using frozen key.
 map.set(key, 1);
 assertTrue(map.has(key));
 assertSame(1, map.get(key));
 
 // Try deleting using frozen key.
 map.delete(key, 1);
 assertFalse(map.has(key));
 assertSame(undefined, map.get(key));