Remove some pause-related fields in a PRODUCT build

runtime/vm/dart.cc

Index: runtime/vm/dart.cc
diff --git a/runtime/vm/dart.cc b/runtime/vm/dart.cc
index d61096f39aa88964d84da9b4994f1d9a6eabc3bd..3949b8b51bdd18fe013d054b835201a33f3ee0d1 100644
--- a/runtime/vm/dart.cc
+++ b/runtime/vm/dart.cc
@@ -610,11 +610,13 @@ RawError* Dart::InitializeIsolate(const uint8_t* snapshot_data,
   is_kernel_isolate = KernelIsolate::IsKernelIsolate(I);
 #endif
   ServiceIsolate::MaybeMakeServiceIsolate(I);
+#if !defined(PRODUCT)
   if (!ServiceIsolate::IsServiceIsolate(I) && !is_kernel_isolate) {
     I->message_handler()->set_should_pause_on_start(
         FLAG_pause_isolates_on_start);
     I->message_handler()->set_should_pause_on_exit(FLAG_pause_isolates_on_exit);
   }
+#endif  // !defined(PRODUCT)
 
   ServiceIsolate::SendIsolateStartupMessage();
 #if !defined(PRODUCT)