Fix Unhandled ReferenceError in debug-debugger.js

src/debug-debugger.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Default number of frames to include in the response to backtrace request.
 var kDefaultBacktraceLength = 10;
 
 var Debug = {};
 
 // Regular expression to skip "crud" at the beginning of a source line which is
@@ skipping 414 matching lines @@
   }
 
   // Convert the line and column into an absolute position within the script.
   var position = Debug.findScriptSourcePosition(script, this.line(), column);
 
   // If the position is not found in the script (the script might be shorter
   // than it used to be) just ignore it.
   if (IS_NULL(position)) return;
 
   // Create a break point object and set the break point.
-  break_point = MakeBreakPoint(position, this);
+  var break_point = MakeBreakPoint(position, this);
   break_point.setIgnoreCount(this.ignoreCount());
   var actual_position = %SetScriptBreakPoint(script, position,
                                              this.position_alignment_,
                                              break_point);
   if (IS_UNDEFINED(actual_position)) {
     actual_position = position;
   }
   var actual_location = script.locationFromPosition(actual_position, true);
   break_point.actual_location = { line: actual_location.line,
                                   column: actual_location.column,
@@ skipping 2134 matching lines @@
 
     default:
       json = null;
   }
   return json;
 }
 
 Debug.TestApi = {
   CommandProcessorResolveValue: DebugCommandProcessor.resolveValue_
 };