V8 JavaScript shared memory prototype.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index c8b275397370d3eb842332a0e5a0e5957ff3678f..6bb0279c69722550aaadd38dc2d3daf23405a72e 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -10054,6 +10054,9 @@ class JSArrayBuffer: public JSObject {
   inline bool should_be_freed();
   inline void set_should_be_freed(bool value);
 
+  inline bool is_shared();
+  inline void set_is_shared(bool value);
+
   // [weak_next]: linked list of array buffers.
   DECL_ACCESSORS(weak_next, Object)
 
@@ -10084,6 +10087,7 @@ class JSArrayBuffer: public JSObject {
   // Bit position in a flag
   static const int kIsExternalBit = 0;
   static const int kShouldBeFreed = 1;
+  static const int kShared = 2;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSArrayBuffer);
 };