Don't quote the arguments to xvfb

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 139 matching lines @@
   step_name = '%s-%s tests %s' % (name, runtime, ' '.join(flags))
   return step_name.strip()
 
 
 IsFirstTestStepCall = True
 def TestStep(name, mode, system, compiler, runtime, targets, flags, arch):
   step_name = TestStepName(name, runtime, flags)
   with bot.BuildStep(step_name, swallow_error=True):
     sys.stdout.flush()
     if NeedsXterm(compiler, runtime) and system == 'linux':
-      cmd = ['xvfb-run', '-a', '--server-args="-screen 0 1024x768x24"']
+      cmd = ['xvfb-run', '-a', '--server-args=-screen 0 1024x768x24']
     else:
       cmd = []
 
     user_test = os.environ.get('USER_TEST', 'no')
 
     cmd.extend([sys.executable,
                 os.path.join(os.curdir, 'tools', 'test.py'),
                 '--step_name=' + step_name,
                 '--mode=' + mode,
                 '--compiler=' + compiler,
@@ skipping 209 matching lines @@
     if build_info.mode == 'debug':
       target = 'dart2js_bot_debug'
     args = [sys.executable, './tools/build.py', '--mode=' + build_info.mode,
             '--arch=' + build_info.arch, target]
     print 'Build SDK and d8: %s' % (' '.join(args))
     bot.RunProcess(args)
 
 
 if __name__ == '__main__':
   bot.RunBot(GetBuildInfo, RunCompilerTests, build_step=BuildCompiler)