Add step OverAwait to service protocol

runtime/vm/service_event.h

Index: runtime/vm/service_event.h
diff --git a/runtime/vm/service_event.h b/runtime/vm/service_event.h
index 45ebb718babd111a2ca5fc1074c4a5a8786c2614..e5afb6d0deb5f857733c9580adaedec4a4ebf416 100644
--- a/runtime/vm/service_event.h
+++ b/runtime/vm/service_event.h
@@ -134,14 +134,6 @@ class ServiceEvent {
     exception_ = exception;
   }
 
-  const Object* async_continuation() const {
-    return async_continuation_;
-  }
-  void set_async_continuation(const Object* closure) {
-    ASSERT(kind_ == kPauseBreakpoint);
-    async_continuation_ = closure;
-  }
-
   bool at_async_jump() const {
     return at_async_jump_;
   }
@@ -203,7 +195,6 @@ class ServiceEvent {
   ActivationFrame* top_frame_;
   const String* extension_rpc_;
   const Object* exception_;
-  const Object* async_continuation_;
   bool at_async_jump_;
   const Object* inspectee_;
   const Heap::GCStats* gc_stats_;