Automagically change the meaning of 'next' to 'async-next' when paused at an async function at awai…

runtime/vm/debugger.cc

Index: runtime/vm/debugger.cc
diff --git a/runtime/vm/debugger.cc b/runtime/vm/debugger.cc
index 5573f4bd9e0475cf5c09f63077ed897f74ebd8a6..2855c1826009d6cc2882bb3f356cdadf2be7bba2 100644
--- a/runtime/vm/debugger.cc
+++ b/runtime/vm/debugger.cc
@@ -2395,7 +2395,17 @@ void Debugger::SignalPausedEvent(ActivationFrame* top_frame,
   event.set_top_frame(top_frame);
   event.set_breakpoint(bpt);
   Object& closure_or_null = Object::Handle(top_frame->GetAsyncOperation());
-  event.set_async_continuation(&closure_or_null);
+  if (!closure_or_null.IsNull()) {
+    event.set_async_continuation(&closure_or_null);
+    const Script& script = Script::Handle(top_frame->SourceScript());
+    const TokenStream& tokens = TokenStream::Handle(script.tokens());
+    TokenStream::Iterator iter(tokens, top_frame->TokenPos());
+    if ((iter.CurrentTokenKind() == Token::kIDENT) &&
+        ((iter.CurrentLiteral() == Symbols::Await().raw()) ||
+         (iter.CurrentLiteral() == Symbols::YieldKw().raw()))) {
+      event.set_at_async_jump(true);
+    }
+  }
   Pause(&event);
 }