Remove old stack-walking code. The new code seems to be doing fine.

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 149 matching lines @@
 
   intptr_t NumLocalVariables();
 
   void VariableAt(intptr_t i,
                   String* name,
                   intptr_t* token_pos,
                   intptr_t* end_pos,
                   Instance* value);
 
   RawArray* GetLocalVariables();
-  RawContext* GetSavedEntryContext(const Context& ctx);
-  RawContext* GetSavedEntryContextNew();
+  RawContext* GetSavedEntryContext();
   RawContext* GetSavedCurrentContext();
 
  private:
   intptr_t PcDescIndex();
   intptr_t TryIndex();
   void GetPcDescriptors();
   void GetVarDescriptors();
   void GetDescIndices();
 
   RawObject* GetLocalVar(intptr_t slot_index);
@@ skipping 197 matching lines @@
                                         intptr_t token_pos);
   void MakeCodeBreakpointsAt(const Function& func,
                              intptr_t token_pos,
                              SourceBreakpoint* bpt);
   // Returns NULL if no breakpoint exists for the given address.
   CodeBreakpoint* GetCodeBreakpoint(uword breakpoint_address);
 
   void SyncBreakpoint(SourceBreakpoint* bpt);
 
   ActivationFrame* TopDartFrame() const;
-  static DebuggerStackTrace* CollectStackTrace();
   static ActivationFrame* CollectDartFrame(Isolate* isolate,
                                            uword pc,
                                            StackFrame* frame,
                                            const Code& code,
                                            const Array& deopt_frame,
                                            intptr_t deopt_frame_offset,
                                            ActivationFrame* callee_activation,
                                            const Context& entry_ctx);
   static RawArray* DeoptimizeToArray(Isolate* isolate,
                                      StackFrame* frame,
                                      const Code& code);
-  static DebuggerStackTrace* CollectStackTraceNew();
+  static DebuggerStackTrace* CollectStackTrace();
   void SignalBpResolved(SourceBreakpoint *bpt);
   void SignalPausedEvent(ActivationFrame* top_frame,
                          SourceBreakpoint* bpt);
 
   intptr_t nextId() { return next_id_++; }
 
   bool ShouldPauseOnException(DebuggerStackTrace* stack_trace,
                               const Instance& exc);
 
   void CollectLibraryFields(const GrowableObjectArray& field_list,
@@ skipping 34 matching lines @@
 
   friend class Isolate;
   friend class SourceBreakpoint;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DEBUGGER_H_