In-object double fields unboxing (for 64-bit only).

src/property.cc

Index: src/property.cc
diff --git a/src/property.cc b/src/property.cc
index 1c42c4929669c89077a6d18a3ef1a21387a82224..cb9eca1362b2d4aa77a053d204f8a34bdd16d42e 100644
--- a/src/property.cc
+++ b/src/property.cc
@@ -56,9 +56,34 @@ OStream& operator<<(OStream& os, const LookupResult& r) {
 }
 
 
+OStream& operator<<(OStream& os, const PropertyDetails& details) {
+  switch (details.type()) {
+    case NORMAL:
+      os << "(normal, dictionary_index: " << details.dictionary_index() << ")";
+      break;
+    case CONSTANT:
+      os << "(constant)\n";
+      break;
+    case FIELD:
+      os << "(field, field_index: " << details.field_index() << ", "
+         << details.representation().Mnemonic() << ")";
+      break;
+    case CALLBACKS:
+      os << "(callbacks)";
+      break;
+    case HANDLER:
+    case INTERCEPTOR:
+    case NONEXISTENT:
+      UNREACHABLE();
+      break;
+  }
+  return os;
+}
+
+
 OStream& operator<<(OStream& os, const Descriptor& d) {
   return os << "Descriptor " << Brief(*d.GetKey()) << " @ "
-            << Brief(*d.GetValue());
+            << Brief(*d.GetValue()) << " " << d.GetDetails();
 }
 
 } }  // namespace v8::internal