Fix two 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 651 matching lines @@
                                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 ShouldPauseOnAsyncException(DebuggerStackTrace* stack_trace,
-                                   const Instance& exc);
-
   bool ShouldPauseOnException(DebuggerStackTrace* stack_trace,
                               const Instance& exc);
 
   void CollectLibraryFields(const GrowableObjectArray& field_list,
                             const Library& lib,
                             const String& prefix,
                             bool include_private_fields);
 
   // Handles any events which pause vm execution.  Breakpoints,
   // interrupts, etc.
@@ skipping 73 matching lines @@
 
   friend class Isolate;
   friend class BreakpointLocation;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_DEBUGGER_H_