[tools] Fix callstats.py script

tools/callstats.py

 #!/usr/bin/env python
 # Copyright 2016 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.
 '''
 Usage: callstats.py [-h] <command> ...
 
 Optional arguments:
   -h, --help  show this help message and exit
 
@@ skipping 377 matching lines @@
     # Calculate the V8-Total (all groups except Callback)
     group_data = { 'time': 0, 'count': 0 }
     for group_name, regexp in groups:
       if group_name == 'Group-Callback': continue
       group_data['time'] += entries[group_name]['time']
       group_data['count'] += entries[group_name]['count']
     entries['Group-Total-V8'] = group_data
     # Calculate the Parse-Total group
     group_data = { 'time': 0, 'count': 0 }
     for group_name, regexp in groups:
-      if !group_name.startswith('Group-Parse'): continue
+      if not group_name.startswith('Group-Parse'): continue
       group_data['time'] += entries[group_name]['time']
       group_data['count'] += entries[group_name]['count']
     entries['Group-Parse-Total'] = group_data
     # Append the sums as single entries to domain.
     for key in entries:
       if key not in domain: domain[key] = { 'time_list': [], 'count_list': [] }
       domain[key]['time_list'].append(entries[key]['time'])
       domain[key]['count_list'].append(entries[key]['count'])
 
 
@@ skipping 279 matching lines @@
     args.error("use either option --sites-file or site URLs")
     sys.exit(1)
   elif args.command == "run" and not coexist(args.replay_wpr, args.replay_bin):
     args.error("options --replay-wpr and --replay-bin must be used together")
     sys.exit(1)
   else:
     args.func(args)
 
 if __name__ == "__main__":
   sys.exit(main())