Delete patch classes once they are applied

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 2bf1aa2a26da0919d847ae777a11f1e92739fccc..4bf089637724c9a40326c79f00b046c3fd16ae42 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -1065,7 +1065,6 @@ class Class : public Object {
   bool IsMixinApplication() const;
 
   RawClass* GetPatchClass() const;
-  void SetPatchClass(const Class& patch_class) const;
 
   // Interfaces is an array of Types.
   RawArray* interfaces() const { return raw_ptr()->interfaces_; }
@@ -3395,6 +3394,10 @@ class Library : public Object {
   void SetLoadError(const Instance& error) const;
   RawInstance* TransitiveLoadError() const;
 
+  void AddPatchClass(const Class& cls) const;
+  RawClass* GetPatchClass(const String& name) const;
+  void RemovePatchClass(const Class& cls) const;
+
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawLibrary));
   }