Revert "Make Function.length and Function.name configurable properties."

test/mjsunit/regress/regress-270142.js

 // Copyright 2013 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 21 matching lines @@
   return x;
 }
 
 function g(x) {
   "use strict";
   return x;
 }
 
 function checkNameDescriptor(f) {
   var descriptor = Object.getOwnPropertyDescriptor(f, "name");
-  assertTrue(descriptor.configurable);
+  assertFalse(descriptor.configurable);
   assertFalse(descriptor.enumerable);
   assertFalse(descriptor.writable);
 }
 
 checkNameDescriptor(f);
 checkNameDescriptor(g);