Fix _first_enum_value usage on make_css_property_names.py

Source/build/scripts/make_css_property_names.py

 #!/usr/bin/env python
 
 import subprocess
 import sys
 
 import css_properties
 import in_generator
 import license
 
 
@@ skipping 185 matching lines @@
             'last_property_id': self._first_enum_value + len(self._properties) - 1,
             'last_unresolved_property_id': max(property["enum_value"] for property in self._properties_including_aliases),
             'max_name_length': max(map(len, self._properties)),
         }
 
     def generate_implementation(self):
         enum_value_to_name = {property['enum_value']: property['name'] for property in self._properties_including_aliases}
         property_offsets = []
         property_names = []
         current_offset = 0
-        for enum_value in range(1, max(enum_value_to_name) + 1):
+        for enum_value in range(self._first_enum_value, max(enum_value_to_name) + 1):
             property_offsets.append(current_offset)
             if enum_value in enum_value_to_name:
                 name = enum_value_to_name[enum_value]
                 property_names.append(name)
                 current_offset += len(name) + 1
 
         css_name_and_enum_pairs = [(property['name'], property['property_id']) for property in self._properties_including_aliases]
 
         gperf_input = GPERF_TEMPLATE % {
             'license': license.license_for_generated_cpp(),
             'class_name': self.class_name,
             'property_name_strings': '\n'.join('    "%s\\0"' % name for name in property_names),
             'property_name_offsets': '\n'.join('    %d,' % offset for offset in property_offsets),
             'property_to_enum_map': '\n'.join('%s, %s' % property for property in css_name_and_enum_pairs),
         }
         # FIXME: If we could depend on Python 2.7, we would use subprocess.check_output
         gperf_args = [self.gperf_path, '--key-positions=*', '-P', '-n']
         gperf_args.extend(['-m', '50'])  # Pick best of 50 attempts.
         gperf_args.append('-D')  # Allow duplicate hashes -> More compact code.
         gperf = subprocess.Popen(gperf_args, stdin=subprocess.PIPE, stdout=subprocess.PIPE, universal_newlines=True)
         return gperf.communicate(gperf_input)[0]
 
 
 if __name__ == "__main__":
     in_generator.Maker(CSSPropertyNamesWriter).main(sys.argv)