Background compilation work:

runtime/vm/flow_graph_optimizer.cc

Index: runtime/vm/flow_graph_optimizer.cc
diff --git a/runtime/vm/flow_graph_optimizer.cc b/runtime/vm/flow_graph_optimizer.cc
index 8bee936ff342ba02d509e93c266030de0b44c72b..e9420e8dffde5c9a9de4496652fcc7c84536d0a5 100644
--- a/runtime/vm/flow_graph_optimizer.cc
+++ b/runtime/vm/flow_graph_optimizer.cc
@@ -4619,7 +4619,8 @@ void FlowGraphOptimizer::VisitStoreInstanceField(
         }
       }
       field.set_is_unboxing_candidate(false);
-      field.DeoptimizeDependentCode();
+      // Delay deoptimization of dependent code to the code installation time.
+      flow_graph()->deoptimize_dependent_code().Add(&field);
     } else {
       FlowGraph::AddToGuardedFields(flow_graph_->guarded_fields(), &field);
     }