Add webkitpy platform support for Mac 10.10 Yosemite.

Tools/Scripts/webkitpy/common/system/platforminfo.py

 # Copyright (c) 2011 Google Inc. 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
@@ skipping 120 matching lines @@
         raise AssertionError('unrecognized platform string "%s"' % sys_platform)
 
     def _determine_mac_version(self, mac_version_string):
         release_version = int(mac_version_string.split('.')[1])
         version_strings = {
             5: 'leopard',
             6: 'snowleopard',
             7: 'lion',
             8: 'mountainlion',
             9: 'mavericks',
+            10: 'yosemite',
         }
         assert release_version >= min(version_strings.keys())
         return version_strings.get(release_version, 'future')
 
     def _determine_linux_version(self):
         # FIXME: we ignore whatever the real version is and pretend it's lucid for now.
         return 'lucid'
 
     def _determine_win_version(self, win_version_tuple):
         if win_version_tuple[:3] == (6, 1, 7600):
             return '7sp0'
         if win_version_tuple[:2] == (6, 0):
             return 'vista'
         if win_version_tuple[:2] == (5, 1):
             return 'xp'
         assert win_version_tuple[0] > 6 or win_version_tuple[1] >= 1, 'Unrecognized Windows version tuple: "%s"' % (win_version_tuple,)
         return 'future'
 
     def _win_version_tuple(self, sys_module):
         if hasattr(sys_module, 'getwindowsversion'):
             return sys_module.getwindowsversion()
         return self._win_version_tuple_from_cmd()
 
     def _win_version_tuple_from_cmd(self):
         # Note that this should only ever be called on windows, so this should always work.
         ver_output = self._executive.run_command(['cmd', '/c', 'ver'], decode_output=False)
         match_object = re.search(r'(?P<major>\d+)\.(?P<minor>\d)\.(?P<build>\d+)', ver_output)
         assert match_object, 'cmd returned an unexpected version string: ' + ver_output
         return tuple(map(int, match_object.groups()))