Enable "strict mode"; for debugger scripts

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.
+"use strict";
 
 // 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
 // not really code. Currently the regular expression matches whitespace and
 // comments.
 var sourceLineBeginningSkip = /^(?:\s*(?:\/\*.*?\*\/)*)*/;
@@ skipping 651 matching lines @@
     break_point.setCondition(opt_condition);
     return break_point.number();
   }
 };
 
 
 Debug.setBreakPointByScriptIdAndPosition = function(script_id, position,
                                                     condition, enabled,
                                                     opt_position_alignment)
 {
-  break_point = MakeBreakPoint(position);
+  var break_point = MakeBreakPoint(position);
   break_point.setCondition(condition);
   if (!enabled) {
     break_point.disable();
   }
   var scripts = this.scripts();
   var position_alignment = IS_UNDEFINED(opt_position_alignment)
       ? Debug.BreakPositionAlignment.Statement : opt_position_alignment;
   for (var i = 0; i < scripts.length; i++) {
     if (script_id == scripts[i].id) {
       break_point.actual_position = %SetScriptBreakPoint(scripts[i], position,
@@ skipping 46 matching lines @@
     break_point = this.findScriptBreakPoint(break_point_number, true);
     if (!break_point) {
       throw new Error('Invalid breakpoint');
     }
   }
 };
 
 
 Debug.clearAllBreakPoints = function() {
   for (var i = 0; i < break_points.length; i++) {
-    break_point = break_points[i];
+    var break_point = break_points[i];
     %ClearBreakPoint(break_point);
   }
   break_points = [];
 };
 
 
 Debug.disableAllBreakPoints = function() {
   // Disable all user defined breakpoints:
   for (var i = 1; i < next_break_point_number; i++) {
     Debug.disableBreakPoint(i);
@@ skipping 1827 matching lines @@
 
     default:
       json = null;
   }
   return json;
 }
 
 Debug.TestApi = {
   CommandProcessorResolveValue: DebugCommandProcessor.resolveValue_
 };