Allow import of .gitignore from wpt.

third_party/WebKit/Tools/Scripts/webkitpy/w3c/test_copier.py

 # Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
 # are met:
 #
 # 1. Redistributions of source code must retain the above
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 #    disclaimer.
 # 2. Redistributions in binary form must reproduce the above
@@ skipping 121 matching lines @@
                 path_base = self.destination_directory.replace(self.layout_tests_dir + '/', '') + '/' + path_base
                 if path_base in paths_to_skip:
                     if self.import_in_place:
                         _log.debug('Pruning: %s', path_base)
                         self.filesystem.remove(path_full)
                         continue
                     else:
                         continue
                 # FIXME: This block should really be a separate function, but the early-continues make that difficult.
 
-                if filename.startswith('.') or filename.endswith('.pl'):
+                # TODO(qyearsley): Remove the below block.
+                if filename.startswith('.gitkeep') or filename.endswith('.pl'):

[jeffcarp, 2017/03/07 01:17:11]

As we talked about in person, I think it would be less risky to make this
exclude all dotfiles except .gitignore.

                     _log.debug('Skipping: %s', path_full)
                     _log.debug('  Reason: Hidden files and perl scripts are not necessary.')
                     continue
+
                 if filename == 'OWNERS' or filename == 'reftest.list':
                     # See http://crbug.com/584660 and http://crbug.com/582838.
                     _log.debug('Skipping: %s', path_full)
                     _log.debug('  Reason: This file may cause Chromium presubmit to fail.')
                     continue
 
                 mimetype = mimetypes.guess_type(path_full)
                 if ('html' not in str(mimetype[0]) and
                         'application/xhtml+xml' not in str(mimetype[0]) and
                         'application/xml' not in str(mimetype[0])):
@@ skipping 165 matching lines @@
             return False
 
         # Conversion is not necessary for any tests in wpt now; see http://crbug.com/654081.
         # Note, we want to move away from converting files, see http://crbug.com/663773.
         if re.search(r'[/\\]external[/\\]wpt[/\\]', dest_dir):
             return False
 
         # Only HTML, XHTML and CSS files should be converted.
         mimetype, _ = mimetypes.guess_type(source_path)
         return mimetype in ('text/html', 'application/xhtml+xml', 'text/css')