Make setting of accessors even more atomic.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index c852b97964916c618094685e64220d3a243134ca..3515b7565bc27793d9ec339d68a092f496d1b96c 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -3065,7 +3065,9 @@ bool Object::SetAccessor(Handle<String> name,
                                                      getter, setter, data,
                                                      settings, attributes);
   i::Handle<i::Object> result = i::SetAccessor(Utils::OpenHandle(this), info);
-  return !result.is_null() && !result->IsUndefined();
+  if (result.is_null() || result->IsUndefined()) return false;
+  i::JSObject::TransformToFastProperties(Utils::OpenHandle(this), 0);

[Michael Starzinger, 2012/03/21 12:33:08]

It would be nice not to have this code duplicated in api.cc and runtime.cc, but
I have no suggestion how to make it cleaner ATM.

[Sven Panne, 2012/03/21 13:14:18]

Well, C++'s abstraction capabilities are extremely restricted, you basically
have to define a class for everything. In our concrete example, we would need a
bracket-like structure (using Andreas' favorite strategy pattern ;-), keeping
the previous "fastness" as the local state. Not complicated, but a kind of a
sledge-hammer for this, so I'll leave this as-is (as discussed offline).

+  return true;
 }