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

runtime/vm/debugger.h

Index: runtime/vm/debugger.h
diff --git a/runtime/vm/debugger.h b/runtime/vm/debugger.h
index 79a620c7bcee6ee9f74c367b1ae5e966357e38da..15893d19966d39c5ef8986a2a07f4d08d446d0b6 100644
--- a/runtime/vm/debugger.h
+++ b/runtime/vm/debugger.h
@@ -354,7 +354,8 @@ class DebuggerEvent {
         top_frame_(NULL),
         breakpoint_(NULL),
         exception_(NULL),
-        async_continuation_(NULL) {}
+        async_continuation_(NULL),
+        at_async_jump_(false) {}
 
   Isolate* isolate() const { return isolate_; }
 
@@ -402,6 +403,13 @@ class DebuggerEvent {
     async_continuation_ = closure;
   }
 
+  bool at_async_jump() const {
+    return at_async_jump_;
+  }
+  void set_at_async_jump(bool value) {
+    at_async_jump_ = value;
+  }
+
   Dart_Port isolate_id() const {
     return isolate_->main_port();
   }
@@ -413,6 +421,7 @@ class DebuggerEvent {
   Breakpoint* breakpoint_;
   const Object* exception_;
   const Object* async_continuation_;
+  bool at_async_jump_;
 };