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..0910e903edf59bb95a58db2f01b2a363a1605083 100644
--- a/runtime/vm/raw_object.h
+++ b/runtime/vm/raw_object.h
@@ -439,6 +439,7 @@ class RawObject {
 
   friend class Api;
   friend class Array;
+  friend class Code;
   friend class FreeListElement;
   friend class GCMarker;
   friend class ExternalTypedData;
@@ -816,7 +817,10 @@ class RawCode : public RawObject {
     return reinterpret_cast<RawObject**>(&ptr()->instructions_);
   }
   RawInstructions* instructions_;
-  RawFunction* function_;
+  // If owner_ is Function::null() the owner is a regular stub.
+  // If owner_ is a Class the owner is the allocation stub for that class.
+  // Else, owner_ is a regular Dart Function.
+  RawObject* owner_;  // Function, Null, or a Class.
   RawExceptionHandlers* exception_handlers_;
   RawPcDescriptors* pc_descriptors_;
   RawArray* deopt_info_array_;