IDL: Drop [PerContextEnabled] extended attribute

Source/bindings/scripts/generate_global_constructors.py

 #!/usr/bin/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.
 
 """Generates interface properties on global objects.
 
 Concretely these are implemented as "constructor attributes", meaning
 "attributes whose name ends with Constructor" (special-cased by code generator),
@@ skipping 85 matching lines @@
         # Exposed=env or Exposed=(env1,...) case
         exposed_global_names = extended_attributes.get('Exposed', 'Window').strip('()').split(',')
         new_constructors_list = generate_global_constructors_list(interface_name, extended_attributes)
         for name in exposed_global_names:
             global_name_to_constructors[name].extend(new_constructors_list)
 
 
 def generate_global_constructors_list(interface_name, extended_attributes):
     extended_attributes_list = [
             name + '=' + extended_attributes[name]
-            for name in 'Conditional', 'PerContextEnabled', 'RuntimeEnabled'
+            for name in 'Conditional', 'RuntimeEnabled'
             if name in extended_attributes]
     if extended_attributes_list:
         extended_string = '[%s] ' % ', '.join(extended_attributes_list)
     else:
         extended_string = ''
 
     attribute_string = 'attribute {interface_name}Constructor {interface_name}'.format(interface_name=interface_name)
     attributes_list = [extended_string + attribute_string]
 
     # In addition to the usual interface property, for every [NamedConstructor]
@@ skipping 64 matching lines @@
         constructors = interface_name_to_constructors(interface_name)
         write_global_constructors_partial_interface(
             interface_name,
             idl_filename,
             constructors,
             options.write_file_only_if_changed)
 
 
 if __name__ == '__main__':
     sys.exit(main())