Implemented schema change for the isolate reload operation.

runtime/vm/become.h

Index: runtime/vm/become.h
diff --git a/runtime/vm/become.h b/runtime/vm/become.h
index b78524d1e1fbf411030a0d5ab42db74dba52e963..8ce164e688c0010bb1cdc72804d23721da29796d 100644
--- a/runtime/vm/become.h
+++ b/runtime/vm/become.h
@@ -80,6 +80,11 @@ class Become : public AllStatic {
   // in 'after'. Every element in 'before' is guaranteed to be not reachable.
   // Useful for atomically applying behavior and schema changes.
   static void ElementsForwardIdentity(const Array& before, const Array& after);
+
+  // Convert and instance object into a dummy object,
+  // making the instance independent of its class.
+  // (used for morphic instances during reload).
+  static void MakeDummyObject(const Instance& instance);
 };
 
 }  // namespace dart