bindings: Throw TypeError when required dictionary member is undefined

Source/bindings/scripts/v8_dictionary.py

 # 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.
 
 """Generate template contexts of dictionaries for both v8 bindings and
 implementation classes that are used by blink's core/modules.
 """
 
 import operator
 from idl_types import IdlType
@@ skipping 62 matching lines @@
             'parent_v8_class': v8_types.v8_type(parent_cpp_class),
         })
     return context
 
 
 def member_context(dictionary, member):
     idl_type = member.idl_type
     idl_type.add_includes_for_type()
     unwrapped_idl_type = unwrap_nullable_if_needed(idl_type)
 
+    if member.is_required and member.default_value:
+        raise Exception(
+            'Required member %s must not have a default value.' % member.name)
+
     def default_values():
         if not member.default_value:
             return None, None
         if member.default_value.is_null:
             return None, 'v8::Null(isolate)'
         cpp_default_value = unwrapped_idl_type.literal_cpp_value(
             member.default_value)
         v8_default_value = unwrapped_idl_type.cpp_value_to_v8_value(
             cpp_value=cpp_default_value, isolate='isolate',
             creation_context='creationContext')
@@ skipping 10 matching lines @@
             cpp_value='impl.%s()' % cpp_name, isolate='isolate',
             creation_context='creationContext',
             extended_attributes=member.extended_attributes),
         'deprecate_as': v8_utilities.deprecate_as(member),
         'enum_validation_expression': unwrapped_idl_type.enum_validation_expression,
         'has_method_name': has_method_name_for_dictionary_member(member),
         'idl_type': idl_type.base_type,
         'is_interface_type': idl_type.is_interface_type and not idl_type.is_dictionary,
         'is_nullable': idl_type.is_nullable,
         'is_object': unwrapped_idl_type.name == 'Object',
+        'is_required': member.is_required,
         'name': member.name,
         'setter_name': setter_name_for_dictionary_member(member),
         'null_setter_name': null_setter_name_for_dictionary_member(member),
         'v8_default_value': v8_default_value,
         'v8_value_to_local_cpp_value': unwrapped_idl_type.v8_value_to_local_cpp_value(
             member.extended_attributes, member.name + 'Value',
             member.name, isolate='isolate', use_exception_state=True),
     }
 
 
@@ skipping 68 matching lines @@
         'getter_expression': getter_expression(),
         'has_method_expression': has_method_expression(),
         'has_method_name': has_method_name_for_dictionary_member(member),
         'is_object': is_object,
         'is_traceable': idl_type.is_traceable,
         'member_cpp_type': member_cpp_type(),
         'null_setter_name': null_setter_name_for_dictionary_member(member),
         'rvalue_cpp_type': idl_type.cpp_type_args(used_as_rvalue_type=True),
         'setter_name': setter_name_for_dictionary_member(member),
     }