Do not accept CSS-wide keywords for descriptors

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):
     defaults = {
         'alias_for': None,
+        'descriptor_only': None,
         'runtime_flag': None,
         'longhands': '',
         'interpolable': False,
         'inherited': False,
         'font': False,
         'svg': False,
         'name_for_methods': None,
         'use_handlers_for': None,
         'getter': None,
         'setter': None,
@@ skipping 23 matching lines @@
         'custom_inherit': (True, False),
         'custom_value': (True, False),
         'builder_skip': (True, False),
         'direction_aware': (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']]
 
         # 0: CSSPropertyInvalid
         # 1: CSSPropertyApplyAtRule
         # 2: CSSPropertyVariable
         self._first_enum_value = 3
 
         # StylePropertyMetadata additionally assumes there are under 1024 properties.
@@ skipping 10 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