Merge bleeding edge up to 8774 into the GC branch.

test/mjsunit/regress/regress-88591.js

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // 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
@@ skipping 22 matching lines @@
 Object.prototype.__defineGetter__('x', function () { return 0; });
 
 this.__proto__ = { x: 1 };
 
 try { fail; } catch (e) { eval('const x = 2'); }
 
 var o = Object.getOwnPropertyDescriptor(this, 'x');
 assertFalse(called);
 assertEquals(2, o.value);
 assertEquals(false, o.writable);