Change safari to be using browser controller on mac, not on linux

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 95 matching lines @@
 def TestStepName(name, flags):
   # Filter out flags with '=' as this breaks the /stats feature of the
   # build bot.
   flags = [x for x in flags if not '=' in x]
   return ('%s tests %s' % (name, ' '.join(flags))).strip()
 
 # TODO(ricow): remove this once we have browser controller drivers for all
 # supported platforms.
 def UseBrowserController(runtime, system):
   supported_platforms = {
-    'linux': ['ff', 'chromeOnAndroid', 'chrome', 'safari'],
-    'mac': [],
+    'linux': ['ff', 'chromeOnAndroid', 'chrome'],
+    'mac': ['safari'],
     'windows': []
   }
   # Platforms that we run on the fyi waterfall only.
   fyi_supported_platforms = {
     'linux': [],
     'mac': [],
     'windows': []
   }
 
   if (runtime in supported_platforms[system]):
@@ skipping 247 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)