Make Dart_GetClass work for private classes.

vm/object.h

Index: vm/object.h
===================================================================
--- vm/object.h	(revision 7921)
+++ vm/object.h	(working copy)
@@ -1737,6 +1737,7 @@
   void AddObject(const Object& obj, const String& name) const;
   RawObject* LookupObject(const String& name) const;
   RawClass* LookupClass(const String& name) const;
+  RawClass* LookupClassAllowPrivate(const String& name) const;

[siva, 2012/05/23 20:59:06]

I am wondering if we should just have
RawClass* LookupPrivateClass(const String& name) const;
here instead of the combo and Dart_GetClass could first
call LookupClass(..);
if this returns null it could then  call LookupPrivateClass(...);

[turnidge, 2012/05/23 21:44:50]

Discussed offline.  I am adding a TODO(turnidge) to go through these functions
and make them more consistent.

   RawObject* LookupLocalObject(const String& name) const;
   RawClass* LookupLocalClass(const String& name) const;
   RawField* LookupFieldAllowPrivate(const String& name) const;