[es6] Function bind should preserve [[Prototype]]

test/mjsunit/function-bind.js

 // Copyright 2010 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 280 matching lines @@
 
 assertThrows(function() { return f.caller; }, TypeError);
 assertThrows(function() { f.caller = 42; }, TypeError);
 assertThrows(function() { return f.arguments; }, TypeError);
 assertThrows(function() { f.arguments = 42; }, TypeError);
 
 // Shouldn't throw. Accessing the functions caller must throw if
 // the caller is strict and the callee isn't. A bound function is built-in,
 // but not considered strict.
 (function foo() { return foo.caller; }).bind()();
+
+
+(function TestProtoIsPreserved() {
+  function fun() {}
+
+  function proto() {}
+  Object.setPrototypeOf(fun, proto);
+  var bound = fun.bind({});
+  assertEquals(proto, Object.getPrototypeOf(bound));
+
+  Object.setPrototypeOf(fun, null);
+  bound = Function.prototype.bind.call(fun, {});
+  assertEquals(null, Object.getPrototypeOf(bound));
+})();