Enable deferred deoptimization always.

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 feb72c182727dddb0a72b8a412e2644f09e3e015..421ff45e2782d026f022a4749d8174503c4b4111 100644
--- a/runtime/vm/flow_graph_optimizer.cc
+++ b/runtime/vm/flow_graph_optimizer.cc
@@ -4654,14 +4654,10 @@ void FlowGraphOptimizer::VisitStoreInstanceField(
         }
       }
       field.set_is_unboxing_candidate(false);
-      if (Compiler::IsBackgroundCompilation()) {
-        // Delay deoptimization of dependent code to the code installation time.
-        // The invalidation of the background compilation result occurs only
-        // when the deoptimization is triggered at code installation.
-        flow_graph()->deoptimize_dependent_code().Add(&field);
-      } else {
-        field.DeoptimizeDependentCode();
-      }
+      // Delay deoptimization of dependent code to the code installation time.
+      // The invalidation of the background compilation result occurs only
+      // when the deoptimization is triggered at code installation.
+      flow_graph()->deoptimize_dependent_code().Add(&field);
     } else {
       FlowGraph::AddToGuardedFields(flow_graph_->guarded_fields(), &field);
     }