Skip presubmits when doing --download-data-only.

tools/run-tests.py

 #!/usr/bin/env python
 #
 # Copyright 2012 the V8 project authors. 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
@@ skipping 325 matching lines @@
   # predefined arch_and_mode since it is more expressive than arch and mode.
   if not options.arch_and_mode:
     options.arch_and_mode = itertools.product(options.arch, options.mode)
 
   # Special processing of other options, sorted alphabetically.
 
   if options.buildbot:
     # Buildbots run presubmit tests as a separate step.
     options.no_presubmit = True
     options.no_network = True
+  if options.download_data_only:
+    options.no_presubmit = True
   if options.command_prefix:
     print("Specifying --command-prefix disables network distribution, "
           "running tests locally.")
     options.no_network = True
   options.command_prefix = shlex.split(options.command_prefix)
   options.extra_flags = shlex.split(options.extra_flags)
 
   if options.gc_stress:
     options.extra_flags += GC_STRESS_FLAGS
 
@@ skipping 291 matching lines @@
   exit_code = runner.Run(options.j)
   overall_duration = time.time() - start_time
 
   if options.time:
     verbose.PrintTestDurations(suites, overall_duration)
   return exit_code
 
 
 if __name__ == "__main__":
   sys.exit(Main())