support .xht directly so we do not have to rename files during w3c imports

Tools/Scripts/webkitpy/layout_tests/port/base.py

 # Copyright (C) 2010 Google Inc. 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
@@ skipping 585 matching lines @@
 
         return expanded_paths
 
     def _real_tests(self, paths):
         # When collecting test cases, skip these directories
         skipped_directories = set(['.svn', '_svn', 'resources', 'script-tests', 'reference', 'reftest'])
         files = find_files.find(self._filesystem, self.layout_tests_dir(), paths, skipped_directories, Port.is_test_file, self.test_key)
         return [self.relative_test_filename(f) for f in files]
 
     # When collecting test cases, we include any file with these extensions.
-    _supported_file_extensions = set(['.html', '.xml', '.xhtml', '.pl',
+    _supported_file_extensions = set(['.html', '.xml', '.xhtml', '.xht', '.pl',

[ojan, 2013/05/22 00:22:06]

Do we not have any tests of what extensions we support?

                                       '.htm', '.php', '.svg', '.mht'])
 
     @staticmethod
     # If any changes are made here be sure to update the isUsedInReftest method in old-run-webkit-tests as well.
     def is_reference_html_file(filesystem, dirname, filename):
         if filename.startswith('ref-') or filename.startswith('notref-'):
             return True
         filename_wihout_ext, unused = filesystem.splitext(filename)
         for suffix in ['-expected', '-expected-mismatch', '-ref', '-notref']:
             if filename_wihout_ext.endswith(suffix):
@@ skipping 892 matching lines @@
 
 class VirtualTestSuite(object):
     def __init__(self, name, base, args, tests=None):
         self.name = name
         self.base = base
         self.args = args
         self.tests = tests or set()
 
     def __repr__(self):
         return "VirtualTestSuite('%s', '%s', %s)" % (self.name, self.base, self.args)