Move prototype metadata from internal properties to prototype maps

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 38 matching lines @@
   if (set__proto__) {
     (new Sub()).__proto__ = proto;
   } else {
     Sub.prototype = proto;
     // Need to instantiate Sub to mark .prototype as prototype.
     new Sub();
   }
 }
 
 
-function test(use_new, add_first, set__proto__, same_map_as) {
+function test(use_new, add_first, set__proto__) {
   var proto = use_new ? new Super() : {};
 
   // New object is fast.
   assertTrue(%HasFastProperties(proto));
 
   if (add_first) {
     AddProps(proto);
     // Adding this many properties makes it slow.
     assertFalse(%HasFastProperties(proto));
     DoProtoMagic(proto, set__proto__);
     // Making it a prototype makes it fast again.
     assertTrue(%HasFastProperties(proto));
   } else {
     DoProtoMagic(proto, set__proto__);
     // Still fast
     assertTrue(%HasFastProperties(proto));
     AddProps(proto);
-    if (set__proto__) {
-      // After we add all those properties it went slow mode again :-(
-      assertFalse(%HasFastProperties(proto));
-    } else {
-      // .prototype keeps it fast.
-      assertTrue(%HasFastProperties(proto));
-    }
-  }
-  if (same_map_as && !add_first && set__proto__) {
-    assertTrue(%HaveSameMap(same_map_as, proto));
+    // Still fast.
+    assertTrue(%HasFastProperties(proto));
   }
   return proto;
 }
 
 // TODO(mstarzinger): This test fails easily if gc happens at the wrong time.
 gc();
 
 for (var i = 0; i < 4; i++) {
   var set__proto__ = ((i & 1) != 0);
   var use_new = ((i & 2) != 0);
 
   test(use_new, true, set__proto__);
-
-  var last = test(use_new, false, set__proto__);
-  test(use_new, false, set__proto__, last);
+  test(use_new, false, set__proto__);
 }
 
 
 var x = {a: 1, b: 2, c: 3};
 var o = { __proto__: x };
 assertTrue(%HasFastProperties(x));
 for (key in x) {
   assertTrue(key == 'a');
   break;
 }
 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;
 }