Amend regression test.

R=rossberg@chromium.org
BUG=128146
TEST=

Review URL: https://chromiumcodereview.appspot.com/10382196

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11580 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/mjsunit/regress/regress-128146.js

@@ -28,3 +28,11 @@
 Object.defineProperty({},"foo",{set:function(){},configurable:false});
 Object.defineProperty({},"foo",{get:function(){},configurable:false});
 Object.defineProperty({},"foo",{});
+
+// From WebKit layout tests (fast/js/prototypes.html)
+var wasSet = false;
+var o = { };
+o.__defineGetter__("__proto__", function() { wasSet = true });
+o.__proto__;
+assertFalse(wasSet);
+