Again, forgot to save before uploading/comitting (just added a comment)

runtime/vm/code_generator_ia32.cc

Index: runtime/vm/code_generator_ia32.cc
===================================================================
--- runtime/vm/code_generator_ia32.cc	(revision 5898)
+++ runtime/vm/code_generator_ia32.cc	(working copy)
@@ -1545,6 +1545,8 @@
         TestClassAndJump(dst_type_class, &done);  // Uses ECX.
         // Check superclass
         __ movl(ECX, FieldAddress(ECX, Class::super_type_offset()));
+        // Note that supertypes can't be NULL as every Dart instance has
+        // as supertype class Object.

[regis, 2012/03/27 20:18:02]

Does that include a Dart instance of type Object?

[srdjan, 2012/03/27 20:43:40]

Good point, I thought that we cannot allocate instances of class object, but it
seems we can. Will add check. Thanks!

[srdjan, 2012/03/27 20:47:09]

Object.super_type is null, i.e., null object which has null class, so it should
be working fine. No checks needed (discussed offline).

         __ movl(ECX, FieldAddress(ECX, Type::type_class_offset()));
         TestClassAndJump(dst_type_class, &done);  // Uses ECX.
       } else {