[runtime] Always normalize prototype maps that aren't marked as 'should be fast' yet

test/mjsunit/fast-prototype.js

 // Copyright 2012 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 83 matching lines @@
   var set__proto__ = ((i & 1) != 0);
   var use_new = ((i & 2) != 0);
 
   test(use_new, true, set__proto__);
   test(use_new, false, set__proto__);
 }
 
 
 var x = {a: 1, b: 2, c: 3};
 var o = { __proto__: x };
-assertTrue(%HasFastProperties(x));
+assertFalse(%HasFastProperties(x));
 for (key in x) {
   assertTrue(key == 'a');
   break;
 }
+assertTrue(%HasFastProperties(x));
 delete x.b;
 for (key in x) {
   assertTrue(key == 'a');
   break;
 }
 assertTrue(%HasFastProperties(x));
 x.d = 4;
 assertTrue(%HasFastProperties(x));
 for (key in x) {
   assertTrue(key == 'a');
   break;
 }