Use Type in CheckPrototypes.

src/ic-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 131 matching lines @@
     } else if (type->Is(Type::Number())) {
       constructor = context->number_function();
     } else if (type->Is(Type::String())) {
       constructor = context->string_function();
     } else {
       ASSERT(type->Is(Type::Symbol()));
       constructor = context->symbol_function();
     }
     return handle(JSObject::cast(constructor->instance_prototype())->map());
   }
-  return type->AsClass();
+  return TypeToMap(type, isolate);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_IC_INL_H_