Support generating enums shared by multiple ComputedStyle fields.

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

 #!/usr/bin/env python
 # Copyright 2016 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 math
 import sys
 
 import json5_generator
 import template_expander
@@ skipping 69 matching lines @@
     """
     Returns a dictionary of enums to be generated, enum name -> [list of enum values]
     """
     enums = {}
     for property_ in properties:
         # Only generate enums for keyword properties that use the default field_storage_type.
         if property_['keyword_only'] and property_['field_storage_type'] is None:
             enum_name = property_['type_name']
             # From the Blink style guide: Enum members should use InterCaps with an initial capital letter. [names-enum-members]
             enum_values = [('k' + camel_case(k)) for k in property_['keywords']]
+
+            if enum_name in enums:
+                # There's an enum with the same name, check if the enum values are the same
+                assert set(enums[enum_name]) == set(enum_values), \
+                    ("'" + property_['name'] + "' can't have type_name '" + enum_name + "' "
+                     "because it was used by a previous property, but with a different set of keywords. "
+                     "Either give it a different name or ensure the keywords are the same.")
+
             enums[enum_name] = enum_values
 
     return enums
 
 
 def _create_property_field(property_):
     """
     Create a property field from a CSS property and return the Field object.
     """
     property_name = property_['name_for_methods']
@@ skipping 186 matching lines @@
     def generate_base_computed_style_constants(self):
         return {
             'properties': self._properties,
             'enums': self._generated_enums,
             'fields': self._fields,
             'expected_total_field_bytes': self._expected_total_field_bytes,
         }
 
 if __name__ == '__main__':
     json5_generator.Maker(ComputedStyleBaseWriter).main()