Filter frames from debugger stack based on visibility rather than "debuggability" (steppability).

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 199 matching lines @@
   friend class Debugger;
   friend class DebuggerStackTrace;
   DISALLOW_COPY_AND_ASSIGN(ActivationFrame);
 };
 
 
 // Array of function activations on the call stack.
 class DebuggerStackTrace : public ZoneAllocated {
  public:
   explicit DebuggerStackTrace(int capacity)
-      : trace_(capacity),
-        user_trace_(capacity) { }
+      : trace_(capacity) { }
 
-  intptr_t Length() const { return user_trace_.length(); }
+  intptr_t Length() const { return trace_.length(); }
 
   ActivationFrame* FrameAt(int i) const {
-    return user_trace_[i];
+    return trace_[i];
   }
 
   ActivationFrame* GetHandlerFrame(const Instance& exc_obj) const;
 
  private:
-  intptr_t UnfilteredLength() const { return trace_.length(); }
-
-  ActivationFrame* UnfilteredFrameAt(int i) const {
-    return trace_[i];
-  }
-
   void AddActivation(ActivationFrame* frame);
   ZoneGrowableArray<ActivationFrame*> trace_;
-  ZoneGrowableArray<ActivationFrame*> user_trace_;
 
   friend class Debugger;
   DISALLOW_COPY_AND_ASSIGN(DebuggerStackTrace);
 };
 
 
 typedef void BreakpointHandler(Dart_Port isolate_id,
                                SourceBreakpoint* bpt,
                                DebuggerStackTrace* stack);
 
@@ skipping 181 matching lines @@
 
   friend class Isolate;
   friend class SourceBreakpoint;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DEBUGGER_H_