Try disabling test converter to see what changes it still makes.

third_party/WebKit/Tools/Scripts/webkitpy/w3c/test_converter.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
 #    copyright notice, this list of conditions and the following
 #    disclaimer.
 # 2. Redistributions in binary form must reproduce the above
@@ skipping 24 matching lines @@
 
 _log = logging.getLogger(__name__)
 
 
 def convert_for_webkit(new_path, filename, reference_support_info, host=Host()):
     """Converts a file's contents so the Blink layout test runner can run it.
 
     Returns:
       A pair: the list of modified properties, and the modified text if the file was modified, None otherwise.
     """
-    contents = host.filesystem.read_binary_file(filename)
-    converter = _W3CTestConverter(new_path, filename, reference_support_info, host)
-    if filename.endswith('.css'):
-        return converter.add_webkit_prefix_to_unprefixed_properties(contents.decode('utf-8'))
-    else:
-        try:
-            converter.feed(contents.decode('utf-8'))
-        except UnicodeDecodeError:
-            converter.feed(contents.decode('utf-16'))
-        converter.close()
-        return converter.output()
+    pass
 
 
 class _W3CTestConverter(HTMLParser):
     """A HTMLParser subclass which converts a HTML file as it is parsed.
 
     After the feed() method is called, the converted document will be stored
     in converted_data, and can be retrieved with the output() method.
     """
 
     def __init__(self, new_path, filename, reference_support_info, host=Host()):
@@ skipping 147 matching lines @@
         self.converted_data.extend(['&#', name, ';'])
 
     def handle_comment(self, data):
         self.converted_data.extend(['<!--', data, '-->'])
 
     def handle_decl(self, decl):
         self.converted_data.extend(['<!', decl, '>'])
 
     def handle_pi(self, data):
         self.converted_data.extend(['<?', data, '>'])