Allow users of the V8 API to distinguish between unset and undefined HiddenValues

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 8633012ba1ee19d2dcf3281812aec031d0cc3b3b..5265901435a67a697244f6001b7e058ea8e73c3b 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -4734,7 +4734,7 @@ Object* JSObject::GetHiddenProperty(Name* key) {
     // For a proxy, use the prototype as target object.
     Object* proxy_parent = GetPrototype();
     // If the proxy is detached, return undefined.
-    if (proxy_parent->IsNull()) return GetHeap()->undefined_value();
+    if (proxy_parent->IsNull()) return GetHeap()->the_hole_value();
     ASSERT(proxy_parent->IsJSGlobalObject());
     return JSObject::cast(proxy_parent)->GetHiddenProperty(key);
   }
@@ -4748,15 +4748,14 @@ Object* JSObject::GetHiddenProperty(Name* key) {
     if (key == GetHeap()->identity_hash_string()) {
       return inline_value;
     } else {
-      return GetHeap()->undefined_value();
+      return GetHeap()->the_hole_value();
     }
   }
 
-  if (inline_value->IsUndefined()) return GetHeap()->undefined_value();
+  if (inline_value->IsUndefined()) return GetHeap()->the_hole_value();
 
   ObjectHashTable* hashtable = ObjectHashTable::cast(inline_value);
   Object* entry = hashtable->Lookup(key);
-  if (entry->IsTheHole()) return GetHeap()->undefined_value();
   return entry;
 }