[es6] Bound function name

test/mjsunit/function-bind-name.js

 // Copyright 2015 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.
 
 function f() {}
 var fb = f.bind({});
 assertEquals('bound f', fb.name);
-assertEquals('function bound f() { [native code] }', fb.toString());
 
 Object.defineProperty(f, 'name', {value: 42});
 var fb2 = f.bind({});
 assertEquals('bound ', fb2.name);
-assertEquals('function bound () { [native code] }', fb2.toString());
+
+function g() {}
+var gb = g.bind({});
+assertEquals('bound g', gb.name);
+assertEquals('bound f', fb.name);