oops, can't clear pointers

panda/src/tinydisplay/tinyGraphicsStateGuardian.cxx

@@ -434,11 +434,6 @@ end_frame(Thread *current_thread) {
 
   // Evict any textures that exceed our texture memory.
   _textures_lru.begin_epoch();
-
-  // Clear these pointers so we don't have floating pointers between
-  // frames.
-  _current_frame_buffer = NULL;
-  _c->zb = NULL;
 }