Strengthen a few assertions and add zapping of allocated...

src/objects.h

 // Copyright 2006-2009 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 1651 matching lines @@
   // numbers array are the same object, the elements are only swapped
   // once.
   void SwapPairs(FixedArray* numbers, int i, int j);
 
   // Sort prefix of this array and the numbers array as pairs wrt. the
   // numbers.  If the numbers array and the this array are the same
   // object, the prefix of this array is sorted.
   void SortPairs(FixedArray* numbers, uint32_t len);
 
  protected:
-  // Set operation on FixedArray without using write barriers.
+  // Set operation on FixedArray without using write barriers. Can
+  // only be used for storing old space objects or smis.
   static inline void fast_set(FixedArray* array, int index, Object* value);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(FixedArray);
 };
 
 
 // DescriptorArrays are fixed arrays used to hold instance descriptors.
 // The format of the these objects is:
 //   [0]: point to a fixed array with (value, detail) pairs.
@@ skipping 3279 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_