Avoid to run dart code during paused_on_exit

runtime/vm/message_handler.cc

Index: runtime/vm/message_handler.cc
diff --git a/runtime/vm/message_handler.cc b/runtime/vm/message_handler.cc
index 3990b5795a8a93ef441b521adfebdfe4ac35694f..04c45fa56a0468ade29c71782a23ef0c166f0359 100644
--- a/runtime/vm/message_handler.cc
+++ b/runtime/vm/message_handler.cc
@@ -346,6 +346,9 @@ void MessageHandler::TaskCallback() {
         PausedOnStartLocked(&ml, false);
       }
     }
+    if (is_paused_on_exit()) {
+      status = paused_on_exit_status_;
+    }
 #endif
 
     if (status == kOK) {
@@ -381,9 +384,10 @@ void MessageHandler::TaskCallback() {
                 name());
           }
           PausedOnExitLocked(&ml, true);
-          // More messages may have come in while we released the monitor.
-          status = HandleMessages(&ml, false, false);
+          paused_on_exit_status_ = status;
         }
+        // More messages may have come in while we released the monitor.
+        status = HandleMessages(&ml, false, false);
         if (ShouldPauseOnExit(status)) {
           // Still paused.
           ASSERT(oob_queue_->IsEmpty());