LibJS: Refactor ScriptFunction::call() a bit

- Get VM reference once
- Less nesting
- Better variable names

Libraries/LibJS/Runtime/ScriptFunction.cpp

@@ -112,8 +112,10 @@ LexicalEnvironment* ScriptFunction::create_environment()
 
 Value ScriptFunction::call()
 {
+ auto& vm = this->vm();
+
  OwnPtr<Interpreter> local_interpreter;
- Interpreter* interpreter = vm().interpreter_if_exists();
+ Interpreter* interpreter = vm.interpreter_if_exists();
 
  if (!interpreter) {
  local_interpreter = Interpreter::create_with_existing_global_object(global_object());
@@ -122,30 +124,30 @@ Value ScriptFunction::call()
 
  VM::InterpreterExecutionScope scope(*interpreter);
 
- auto& argument_values = vm().call_frame().arguments;
+ auto& call_frame_args = vm.call_frame().arguments;
  ArgumentVector arguments;
  for (size_t i = 0; i < m_parameters.size(); ++i) {
- auto parameter = parameters()[i];
- auto value = js_undefined();
+ auto parameter = m_parameters[i];
+ Value argument_value;
  if (parameter.is_rest) {
  auto* array = Array::create(global_object());
- for (size_t rest_index = i; rest_index < argument_values.size(); ++rest_index)
- array->indexed_properties().append(argument_values[rest_index]);
- value = Value(array);
+ for (size_t rest_index = i; rest_index < call_frame_args.size(); ++rest_index)
+ array->indexed_properties().append(call_frame_args[rest_index]);
+ argument_value = move(array);
+ } else if (i < call_frame_args.size() && !call_frame_args[i].is_undefined()) {
+ argument_value = call_frame_args[i];
+ } else if (parameter.default_value) {
+ argument_value = parameter.default_value->execute(*interpreter, global_object());
+ if (vm.exception())
+ return {};
  } else {
- if (i < argument_values.size() && !argument_values[i].is_undefined()) {
- value = argument_values[i];
- } else if (parameter.default_value) {
- value = parameter.default_value->execute(*interpreter, global_object());
- if (vm().exception())
- return {};
- }
+ argument_value = js_undefined();
  }
- arguments.append({ parameter.name, value });
- vm().current_environment()->set(global_object(), parameter.name, { value, DeclarationKind::Var });
+ arguments.append({ parameter.name, argument_value });
+ vm.current_environment()->set(global_object(), parameter.name, { argument_value, DeclarationKind::Var });
  }
 
- return interpreter->execute_statement(global_object(), m_body, arguments, ScopeType::Function);
+ return interpreter->execute_statement(global_object(), m_body, move(arguments), ScopeType::Function);
 }
 
 Value ScriptFunction::construct(Function&)