Fix so that you can run presubmit.py in Windows.

tools/presubmit.py

 #!/usr/bin/env python
 #
 # Copyright 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
@@ skipping 210 matching lines @@
 
   IGNORE_LINT = ['flag-definitions.h']
 
   def IgnoreFile(self, name):
     return (super(CppLintProcessor, self).IgnoreFile(name)
               or (name in CppLintProcessor.IGNORE_LINT))
 
   def GetPathsToSearch(self):
     return ['src', 'preparser', 'include', 'samples', join('test', 'cctest')]
 
+  def GetCpplintScript(self, prio_path):
+    for path in [prio_path] + os.environ["PATH"].split(os.pathsep):
+      path = path.strip('"')
+      cpplint = os.path.join(path, "cpplint.py")
+      if os.path.isfile(cpplint):
+        return cpplint
+
+    return None
+
   def ProcessFiles(self, files, path):
     good_files_cache = FileContentsCache('.cpplint-cache')
     good_files_cache.Load()
     files = good_files_cache.FilterUnchangedFiles(files)
     if len(files) == 0:
       print 'No changes in files detected. Skipping cpplint check.'
       return True
 
     filt = '-,' + ",".join(['+' + n for n in ENABLED_LINT_RULES])
-    command = ['cpplint.py', '--filter', filt]
-    local_cpplint = join(path, "tools", "cpplint.py")
-    if exists(local_cpplint):
-      command = ['python', local_cpplint, '--filter', filt]
+    command = [sys.executable, 'cpplint.py', '--filter', filt]
+    cpplint = self.GetCpplintScript(join(path, "tools"))
+    if cpplint is None:
+      print('Could not find cpplint.py. Make sure '
+            'depot_tools is installed and in the path.')
+      sys.exit(1)
+
+    command = [sys.executable, cpplint, '--filter', filt]
 
     commands = join([command + [file] for file in files])
     count = multiprocessing.cpu_count()
     pool = multiprocessing.Pool(count)
     try:
       results = pool.map_async(CppLintWorker, commands).get(999999)
     except KeyboardInterrupt:
       print "\nCaught KeyboardInterrupt, terminating workers."
       sys.exit(1)
 
@@ skipping 126 matching lines @@
   print "Running copyright header and trailing whitespaces check..."
   success = SourceProcessor().Run(workspace) and success
   if success:
     return 0
   else:
     return 1
 
 
 if __name__ == '__main__':
   sys.exit(Main())