Add step OverAwait to service protocol

runtime/observatory/lib/src/elements/debugger.dart

Index: runtime/observatory/lib/src/elements/debugger.dart
diff --git a/runtime/observatory/lib/src/elements/debugger.dart b/runtime/observatory/lib/src/elements/debugger.dart
index 3692d6a50c1c3cd1c85729be4d61f154c3ec3bac..3bf25b567eea41e1d2e11dab34f09e09f6f5bcd8 100644
--- a/runtime/observatory/lib/src/elements/debugger.dart
+++ b/runtime/observatory/lib/src/elements/debugger.dart
@@ -1810,7 +1810,7 @@ class ObservatoryDebugger extends Debugger {
   Future smartNext() async {
     if (isolatePaused()) {
       var event = isolate.pauseEvent;
-      if (event.atAsyncJump) {
+      if (event.atAsyncSuspension) {
         return asyncNext();
       } else {
         return syncNext();
@@ -1823,11 +1823,10 @@ class ObservatoryDebugger extends Debugger {
   Future asyncNext() async {
     if (isolatePaused()) {
       var event = isolate.pauseEvent;
-      if (event.asyncContinuation == null) {
+      if (!event.atAsyncSuspension) {
         console.print("No async continuation at this location");
       } else {
-        List<Future> asyncStepFutures = await isolate.asyncStepOver();
-        return asyncStepFutures[Isolate.kFirstResume];
+        return isolate.stepOverAsyncSuspension();
       }
     } else {
       console.print('The program is already running');