IDL: Improve "includes for type" mechanism in various ways

Source/bindings/scripts/v8_union.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.
 
 import v8_utilities
 
 
 UNION_H_INCLUDES = frozenset([
     'bindings/core/v8/Dictionary.h',
     'bindings/core/v8/ExceptionState.h',
@@ skipping 111 matching lines @@
         'interface_types': interface_types,
         'members': members,
         'needs_trace': any(member['is_traceable'] for member in members),
         'numeric_type': numeric_type,
         'string_type': string_type,
         'type_string': str(union_type),
     }
 
 
 def member_context(member, interfaces_info):
-    cpp_includes.update(member.includes_for_type)
+    cpp_includes.update(member.includes_for_type())
     interface_info = interfaces_info.get(member.name, None)
     if interface_info:
         cpp_includes.update(interface_info.get('dependencies_include_paths', []))
         header_forward_decls.add(member.implemented_as)
     if member.is_nullable:
         member = member.inner_type
     return {
         'cpp_name': v8_utilities.uncapitalize(member.name),
         'cpp_type': member.cpp_type_args(used_in_cpp_sequence=True),
         'cpp_local_type': member.cpp_type,
         'cpp_value_to_v8_value': member.cpp_value_to_v8_value(
             cpp_value='impl.getAs%s()' % member.name, isolate='isolate',
             creation_context='creationContext'),
         'enum_values': member.enum_values,
         'is_traceable': member.is_traceable,
         'rvalue_cpp_type': member.cpp_type_args(used_as_rvalue_type=True),
         'specific_type_enum': 'SpecificType' + member.name,
         'type_name': member.name,
         'v8_value_to_local_cpp_value': member.v8_value_to_local_cpp_value(
             {}, 'v8Value', 'cppValue', isolate='isolate',
             use_exception_state=True, restricted_float=True),
     }