Fix a couple of bugs with async stack traces

runtime/vm/debugger.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef RUNTIME_VM_DEBUGGER_H_
 #define RUNTIME_VM_DEBUGGER_H_
 
 #include "include/dart_tools_api.h"
 
 #include "vm/object.h"
@@ skipping 587 matching lines @@
   void PrintBreakpointsToJSONArray(JSONArray* jsarr) const;
   void PrintSettingsToJSONObject(JSONObject* jsobj) const;
 
   static bool IsDebuggable(const Function& func);
 
   intptr_t limitBreakpointId() { return next_id_; }
 
   // Callback to the debugger to continue frame rewind, post-deoptimization.
   void RewindPostDeopt();
 
+  static DebuggerStackTrace* CollectAwaiterReturnStackTrace();
+
  private:
   RawError* PauseRequest(ServiceEvent::EventKind kind);
 
   // Finds the breakpoint we hit at |location|.
   Breakpoint* FindHitBreakpoint(BreakpointLocation* location,
                                 ActivationFrame* top_frame);
 
   // Will return false if we are not at an await.
   bool SetupStepOverAsyncSuspension(const char** error);
 
@@ skipping 54 matching lines @@
   static void AppendCodeFrames(Thread* thread,
                                Isolate* isolate,
                                Zone* zone,
                                DebuggerStackTrace* stack_trace,
                                StackFrame* frame,
                                Code* code,
                                Code* inlined_code,
                                Array* deopt_frame);
   static DebuggerStackTrace* CollectStackTrace();
   static DebuggerStackTrace* CollectAsyncCausalStackTrace();
-  static DebuggerStackTrace* CollectAwaiterReturnStackTrace();
   void SignalPausedEvent(ActivationFrame* top_frame, Breakpoint* bpt);
 
   intptr_t nextId() { return next_id_++; }
 
   bool ShouldPauseOnException(DebuggerStackTrace* stack_trace,
                               const Instance& exc);
 
   void CollectLibraryFields(const GrowableObjectArray& field_list,
                             const Library& lib,
                             const String& prefix,
@@ skipping 79 matching lines @@
 
   friend class Isolate;
   friend class BreakpointLocation;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_DEBUGGER_H_