Remove invalid assertion.

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 06b4b602db56329bf45818070c35266c5980b906..f832cbcb1a452de06ef7199da45fa6e94a28ec9f 100644
--- a/runtime/vm/message_handler.cc
+++ b/runtime/vm/message_handler.cc
@@ -320,10 +320,9 @@ void MessageHandler::TaskCallback() {
       run_end_callback = true;
     }
 
-    // Clear the task_ last.  We don't want any other tasks to start up
-    // until we are done with all messages and pause notifications.
+    // Clear the task_ last.  This allows other tasks to potentially start
+    // for this message handler.
     ASSERT(oob_queue_->IsEmpty());
-    ASSERT(!ok || queue_->IsEmpty());
     task_ = NULL;
   }
   if (run_end_callback && end_callback_ != NULL) {