Add a generated ComputedStyleBase class that ComputedStyle extends

third_party/WebKit/Source/build/scripts/css_properties.py

 #!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import in_generator
 import name_utilities
 
 
 class CSSProperties(in_generator.Writer):
@@ skipping 16 matching lines @@
         'converter': None,
         'custom_all': False,
         'custom_initial': False,
         'custom_inherit': False,
         'custom_value': False,
         'builder_skip': False,
         'direction_aware': False,
         # Typed OM annotations.
         'typedom_types': [],
         'keywords': [],
+        'keyword_only': False,
         'supports_percentage': False,
         'supports_multiple': False,
     }
 
     valid_values = {
         'interpolable': (True, False),
         'inherited': (True, False),
         'independent': (True, False),
         'font': (True, False),
         'svg': (True, False),
         'custom_all': (True, False),
         'custom_initial': (True, False),
         'custom_inherit': (True, False),
         'custom_value': (True, False),
         'builder_skip': (True, False),
         'direction_aware': (True, False),
+        'keyword_only': (True, False),
     }
 
     def __init__(self, file_paths):
         in_generator.Writer.__init__(self, file_paths)
 
         properties = self.in_file.name_dictionaries
         self._descriptors = [property for property in properties if property['descriptor_only']]
 
         self._aliases = [property for property in properties if property['alias_for']]
         properties = [property for property in properties if not property['alias_for']]
@@ skipping 17 matching lines @@
         self._properties = {property['property_id']: property for property in properties}
 
         # The generated code will only work with at most one alias per property
         assert len({property['alias_for'] for property in self._aliases}) == len(self._aliases)
 
         for property in self._aliases:
             property['property_id'] = name_utilities.enum_for_css_property_alias(property['name'])
             aliased_property = self._properties[name_utilities.enum_for_css_property(property['alias_for'])]
             property['enum_value'] = aliased_property['enum_value'] + 512
         self._properties_including_aliases += self._aliases