Fix misleading names and comments in mute local variables debugger helper

src/mirror-debugger.js

 // Copyright 2006-2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1689 matching lines @@
 FrameMirror.prototype.evaluate = function(source, disable_break,
                                           opt_context_object) {
   var result_array = %DebugEvaluate(this.break_id_,
                                     this.details_.frameId(),
                                     this.details_.inlinedFrameIndex(),
                                     source,
                                     Boolean(disable_break),
                                     opt_context_object);
   // Silently ignore local variables changes if the frame is optimized.
   if (!this.isOptimizedFrame()) {
-    var local_scope_before = result_array[1];
-    var local_scope_after = result_array[2];
-    for (var n in local_scope_after) {
-      var value_before = local_scope_before[n];
-      var value_after = local_scope_after[n];
-      if (value_before !== value_after) {
+    var local_scope_on_stack = result_array[1];
+    var local_scope_modifed = result_array[2];
+    for (var n in local_scope_modifed) {
+      var value_on_stack = local_scope_on_stack[n];
+      var value_modifed = local_scope_modifed[n];
+      if (value_on_stack !== value_modifed) {
         %SetScopeVariableValue(this.break_id_,
                                this.details_.frameId(),
                                this.details_.inlinedFrameIndex(),
                                0,
                                n,
-                               value_after);
+                               value_modifed);
       }
     }
   }
   return MakeMirror(result_array[0]);
 };
 
 
 FrameMirror.prototype.invocationText = function() {
   // Format frame invoaction (receiver, function and arguments).
   var result = '';
@@ skipping 930 matching lines @@
   }
   if (!NUMBER_IS_FINITE(value)) {
     if (value > 0) {
       return 'Infinity';
     } else {
       return '-Infinity';
     }
   }
   return value;
 }