Cleanup native, collected, and stub code handling in profiler

runtime/vm/raw_object.h

Index: runtime/vm/raw_object.h
diff --git a/runtime/vm/raw_object.h b/runtime/vm/raw_object.h
index e876e666fef636cc5bc86dfd7d82d0d0552e6d9f..458341d322211cab7b8eacba59bf17c7188662a8 100644
--- a/runtime/vm/raw_object.h
+++ b/runtime/vm/raw_object.h
@@ -816,7 +816,7 @@ class RawCode : public RawObject {
     return reinterpret_cast<RawObject**>(&ptr()->instructions_);
   }
   RawInstructions* instructions_;
-  RawFunction* function_;
+  RawObject* owner_;  // Function, Null, or a smi (class id).
   RawExceptionHandlers* exception_handlers_;
   RawPcDescriptors* pc_descriptors_;
   RawArray* deopt_info_array_;