Change annotated steps to use windows as system no matter if we are on win7 or win8

tools/bots/compiler.py

 #!/usr/bin/python
 
 # Copyright (c) 2012, 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.
 
 """
 Dart2js buildbot steps
 
 Runs tests for the  dart2js compiler.
@@ skipping 62 matching lines @@
       host_checked = True
     if dart2js_pattern.group(8) == 'host-checked':
       host_checked = True
     if dart2js_pattern.group(10) == 'minified':
       minified = True
     shard_index = dart2js_pattern.group(11)
     total_shards = dart2js_pattern.group(12)
   else :
     return None
 
-  if system == 'windows':
-    system = 'win7'
+  # We have both win7 and win8 bots, functionality is the same.
+  if system.startsWith('win'):
+    system = 'windows'
 
   # We have both 10.8 and 10.7 bots, functionality is the same.
   if system == 'mac10.8' or system == 'mac10.7':
     system = 'mac'
 
   if (system == 'win7' and platform.system() != 'Windows') or (
       system == 'mac' and platform.system() != 'Darwin') or (
       system == 'linux' and platform.system() != 'Linux'):
     print ('Error: You cannot emulate a buildbot with a platform different '
         'from your own.')
@@ skipping 283 matching lines @@
   """
   with bot.BuildStep('Build SDK and d8'):
     args = [sys.executable, './tools/build.py', '--mode=' + build_info.mode,
             'dart2js_bot']
     print 'Build SDK and d8: %s' % (' '.join(args))
     bot.RunProcess(args)
 
 
 if __name__ == '__main__':
   bot.RunBot(GetBuildInfo, RunCompilerTests, build_step=BuildCompiler)