Create a separate space for global property cells

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 962 matching lines @@
 
   // During serialization: the map word is used to hold an encoded
   // address, and possibly a mark bit (set and cleared with SetMark
   // and ClearMark).
 
   // Create a map word from an encoded address.
   static inline MapWord FromEncodedAddress(Address address);
 
   inline Address ToEncodedAddress();
 
- private:
-  // HeapObject calls the private constructor and directly reads the value.
-  friend class HeapObject;
-
-  explicit MapWord(uintptr_t value) : value_(value) {}
-
-  uintptr_t value_;
-
   // Bits used by the marking phase of the garbage collector.
   //
   // The first word of a heap object is normally a map pointer. The last two
   // bits are tagged as '01' (kHeapObjectTag). We reuse the last two bits to
   // mark an object as live and/or overflowed:
   //   last bit = 0, marked as alive
   //   second bit = 1, overflowed
   // An object is only marked as overflowed when it is marked as live while
   // the marking stack is overflowed.
   static const int kMarkingBit = 0;  // marking bit
@@ skipping 21 matching lines @@
   static const uint32_t kMapPageIndexMask =
       (1 << kMapPageOffsetShift) - 1;
 
   // 0x001FFC00
   static const uint32_t kMapPageOffsetMask =
       ((1 << kForwardingOffsetShift) - 1) & ~kMapPageIndexMask;
 
   // 0xFFE00000
   static const uint32_t kForwardingOffsetMask =
       ~(kMapPageIndexMask | kMapPageOffsetMask);
+
+ private:
+  // HeapObject calls the private constructor and directly reads the value.
+  friend class HeapObject;
+
+  explicit MapWord(uintptr_t value) : value_(value) {}
+
+  uintptr_t value_;
 };
 
 
 // HeapObject is the superclass for all classes describing heap allocated
 // objects.
 class HeapObject: public Object {
  public:
   // [map]: Contains a map which contains the object's reflective
   // information.
   inline Map* map();
@@ skipping 3473 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_