Updated VM stacktrace support (20898) with strndup impl.

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 VM_DEBUGGER_H_
 #define VM_DEBUGGER_H_
 
 #include "include/dart_debugger_api.h"
 
 #include "vm/object.h"
@@ skipping 316 matching lines @@
                                         intptr_t token_pos);
   CodeBreakpoint* MakeCodeBreakpoint(const Function& func,
                                      intptr_t first_token_pos,
                                      intptr_t last_token_pos);
 
   // Returns NULL if no breakpoint exists for the given address.
   CodeBreakpoint* GetCodeBreakpoint(uword breakpoint_address);
 
   void SyncBreakpoint(SourceBreakpoint* bpt);
 
-  DebuggerStackTrace* CollectStackTrace();
+  static DebuggerStackTrace* CollectStackTrace();
   void SignalBpResolved(SourceBreakpoint *bpt);
 
   bool IsDebuggable(const Function& func);
 
   intptr_t nextId() { return next_id_++; }
 
   bool ShouldPauseOnException(DebuggerStackTrace* stack_trace,
                               const Instance& exc);
 
   void CollectLibraryFields(const GrowableObjectArray& field_list,
@@ skipping 26 matching lines @@
   // Do not call back to breakpoint handler if this flag is set.
   // Effectively this means ignoring breakpoints. Set when Dart code may
   // be run as a side effect of getting values of fields.
   bool ignore_breakpoints_;
 
   intptr_t exc_pause_info_;
 
   static BreakpointHandler* bp_handler_;
   static EventHandler* event_handler_;
 
+  friend class Isolate;
   friend class SourceBreakpoint;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DEBUGGER_H_