Reland "[test] Fix cctest path separators on Windows"

tools/testrunner/local/testsuite.py

 # 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
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 208 matching lines @@
     """
     filtered = []
     globs = []
     exact_matches = []
     for a in args:
       argpath = a.split('/')
       if argpath[0] != self.name:
         continue
       if len(argpath) == 1 or (len(argpath) == 2 and argpath[1] == '*'):
         return  # Don't filter, run all tests in this suite.
-      path = os.path.sep.join(argpath[1:])
+      path = '/'.join(argpath[1:])
       if path[-1] == '*':
         path = path[:-1]
         globs.append(path)
       else:
         exact_matches.append(path)
     for t in self.tests:
       for a in globs:
         if t.path.startswith(a):
           filtered.append(t)
           break
@@ skipping 84 matching lines @@
     return (testcase.flags + ["--gtest_filter=" + testcase.path] +
             ["--gtest_random_seed=%s" % context.random_seed] +
             ["--gtest_print_time=0"] +
             context.mode_flags)
 
   def _VariantGeneratorFactory(self):
     return StandardVariantGenerator
 
   def shell(self):
     return self.name