Support passing DartVM flags via DART_FLAGS.

tools/testing/drt-trampoline.py

+# 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.
+#
+# For now we have to use this trampoline to turn --dart-flags command line
+# switch into env variable DART_FLAGS.  Eventually, DumpRenderTree should
+# support --dart-flags and this hack may go away.
+#
+# Expected invocation: python drt-trampoline.py <path to DRT> <DRT command line>
+
+import os
+import subprocess
+import sys
+
+DART_FLAGS_PREFIX = '--dart-flags='
+
+def main(argv):
+  drt_path = argv[1]
+  command_line = argv[2:]
+
+  cmd = [drt_path]
+
+  env = None
+  for arg in command_line:
+    if arg.startswith(DART_FLAGS_PREFIX):
+      env = dict(os.environ.items())
+      env['DART_FLAGS'] = arg[len(DART_FLAGS_PREFIX):]
+    else:
+      cmd.append(arg)
+
+  p = subprocess.Popen(cmd, env=env)
+  p.wait()
+  if p.returncode != 0:
+    raise Exception('Failed to run command. return code=%s' % p.returncode)
+
+
+if __name__ == '__main__':
+  try:
+    sys.exit(main(sys.argv))
+  except StandardError as e:
+    print 'Fail: ' + str(e)
+    sys.exit(1)