Allocate instance closures similarly to regular closures, i.e. without a

runtime/vm/object.h

Index: runtime/vm/object.h
===================================================================
--- runtime/vm/object.h	(revision 33072)
+++ runtime/vm/object.h	(working copy)
@@ -1510,9 +1510,6 @@
   RawClass* signature_class() const;
   void set_signature_class(const Class& value) const;
 
-  RawCode* closure_allocation_stub() const;
-  void set_closure_allocation_stub(const Code& value) const;
-
   void set_extracted_method_closure(const Function& function) const;
   RawFunction* extracted_method_closure() const;
 
@@ -2007,11 +2004,6 @@
   }
   void set_implicit_static_closure(const Instance& closure) const;
 
-  RawCode* closure_allocation_stub() const {
-    return raw_ptr()->closure_allocation_stub_;
-  }
-  void set_closure_allocation_stub(const Code& value) const;
-
   static RawClosureData* New();
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(ClosureData, Object);