Freeze global prototype chain per WebIDL

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

 {% extends 'interface_base.cpp.tmpl' %}
 
 {% set has_prepare_prototype_and_interface_object =
     unscopables or has_conditional_attributes_on_prototype or
     methods | conditionally_exposed(is_partial) %}
 {% set prepare_prototype_and_interface_object_func =
     '%s::preparePrototypeAndInterfaceObject' % v8_class
     if has_prepare_prototype_and_interface_object
     else 'nullptr' %}
 
@@ skipping 751 matching lines @@
 {% if has_named_properties_object %}
 v8::Local<v8::FunctionTemplate> {{v8_class}}::domTemplateForNamedPropertiesObject(v8::Isolate* isolate, const DOMWrapperWorld& world) {
   v8::Local<v8::FunctionTemplate> parentTemplate = V8{{parent_interface}}::domTemplate(isolate, world);
 
   v8::Local<v8::FunctionTemplate> namedPropertiesObjectFunctionTemplate = v8::FunctionTemplate::New(isolate, V8ObjectConstructor::isValidConstructorMode);
   namedPropertiesObjectFunctionTemplate->SetClassName(v8AtomicString(isolate, "{{interface_name}}Properties"));
   namedPropertiesObjectFunctionTemplate->Inherit(parentTemplate);
 
   v8::Local<v8::ObjectTemplate> namedPropertiesObjectTemplate = namedPropertiesObjectFunctionTemplate->PrototypeTemplate();
   namedPropertiesObjectTemplate->SetInternalFieldCount({{v8_class}}::internalFieldCount);
+  // Named Properties object has SetPrototype method of Immutable Prototype Exotic Objects
+  namedPropertiesObjectTemplate->SetImmutableProto();
   V8DOMConfiguration::setClassString(isolate, namedPropertiesObjectTemplate, "{{interface_name}}Properties");
   {{install_named_property_handler('namedPropertiesObjectTemplate') | indent(2)}}
 
   return namedPropertiesObjectFunctionTemplate;
 }
 
 {% endif %}
 {% endblock %}
 
 
@@ skipping 177 matching lines @@
 }
 
 {% for method in methods if method.overloads and method.overloads.has_partial_overloads %}
 void {{v8_class}}::register{{method.name | blink_capitalize}}MethodForPartialInterface(void (*method)(const v8::FunctionCallbackInfo<v8::Value>&)) {
   {{cpp_class}}V8Internal::{{method.name}}MethodForPartialInterface = method;
 }
 
 {% endfor %}
 {% endif %}
 {% endblock %}