v8binding: Don't allow author script to define indexed accessor prop.

third_party/WebKit/Source/bindings/templates/interface_base.cpp.tmpl

 {% filter format_blink_cpp_source_code %}
 
 {% include 'copyright_block.txt' %}
 #include "{{v8_class_or_partial}}.h"
 
 {% for filename in cpp_includes if filename != '%s.h' % cpp_class_or_partial %}
 #include "{{filename}}"
 {% endfor %}
 
 namespace blink {
@@ skipping 226 matching lines @@
 {% block origin_safe_method_setter_callback %}{% endblock %}
 {# Special operations (methods) #}
 {% block named_property_getter_callback %}{% endblock %}
 {% block named_property_setter_callback %}{% endblock %}
 {% block named_property_deleter_callback %}{% endblock %}
 {% block named_property_query_callback %}{% endblock %}
 {% block named_property_enumerator_callback %}{% endblock %}
 {% block indexed_property_getter_callback %}{% endblock %}
 {% block indexed_property_setter_callback %}{% endblock %}
 {% block indexed_property_deleter_callback %}{% endblock %}
+{% block indexed_property_definer_callback %}{% endblock %}
 
 {% if has_access_check_callbacks and not is_partial %}
 bool {{v8_class_or_partial}}::securityCheck(v8::Local<v8::Context> accessingContext, v8::Local<v8::Object> accessedObject, v8::Local<v8::Value> data) {
   {% if interface_name == 'Window' %}
   v8::Isolate* isolate = v8::Isolate::GetCurrent();
   v8::Local<v8::Object> window = V8Window::findInstanceInPrototypeChain(accessedObject, isolate);
   if (window.IsEmpty())
     return false;  // the frame is gone.
 
   const DOMWindow* targetWindow = V8Window::toImpl(window);
@@ skipping 689 matching lines @@
 {% endif %}
 }
 {% endif %}
 
 {% endblock %}
 {##############################################################################}
 {% block partial_interface %}{% endblock %}
 }  // namespace blink
 
 {% endfilter %}{# format_blink_cpp_source_code #}