Update script to switch through revision history successfully.

tools/testing/webdriver_test_setup.py

 #!/usr/bin/python
 
 # Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 # Run to install the necessary components to run webdriver on the buildbots or
 # on your local machine. 
 # Note: The setup steps can be done fairly easily by hand. This script is 
 # intended to simply and reduce the time for setup since there are a fair number
@@ skipping 90 matching lines @@
     f = urllib2.urlopen(google_code_site)
     latest = ''
     for line in f.readlines():
       if re.search(self.download_regex_str, line):
         suffix_index = line.find(
             self.download_regex_str[self.download_regex_str.rfind('.'):])
         name_end = self.download_regex_str.rfind('.+')
         name = self.download_name_func({'os': self.get_os_str, 'version': ''})
         name = name[:name.rfind('.')]
         version_str = line[line.find(name) + len(name) : suffix_index]
+        orig_version_str = version_str
+        if version_str.count('.') == 0:
+          version_str = version_str.replace('_', '.')
+          version_str = re.compile(r'[^\d.]+').sub('', version_str)
         if latest == '':
           latest = '0.' * version_str.count('.')
           latest += '0'
+          orig_latest_str = latest
+        else:
+          orig_latest_str = latest
+          latest = latest.replace('_', '.')
+          latest = re.compile(r'[^\d.]+').sub('', latest)
         nums = version_str.split('.')
         latest_nums = latest.split('.')
         for (num, latest_num) in zip(nums, latest_nums):
           if int(num) > int(latest_num):
-            latest = version_str
+            latest = orig_version_str
             break
+          else:
+            latest = orig_latest_str
     if latest == '':
       raise Exception("Couldn't find the desired download on " + \
           ' %s.' % google_code_site)
     return latest
 
   def run(self):
     """Download and install the Google Code."""
     print 'Installing from %s' % self.project_name
     os_str = self.get_os_str
     version = self.find_latest_version()
@@ skipping 128 matching lines @@
       lambda x: 'chromedriver_%(os)s_%(version)s.zip' % x).run()
   if 'win32' not in sys.platform and 'cygwin' not in sys.platform:
     GoogleCodeInstaller('selenium', os.path.dirname(os.path.abspath(__file__)),
         lambda x: 'selenium-server-standalone-%(version)s.jar' % x).run()
 
   if args.firefox:
     FirefoxInstaller().run()
 
 if __name__ == '__main__':
   main()