message: Fix windows test again by setting the initial mode to PRECOMPOSITION
  ref: https://github.com/google/mozc/blob/master/src/session/session.cc;rcl=505024918;l=200
diff: @@ -469,6 +469,16 @@ TEST_F(SessionHandlerTest, ConfigTest) {
  uint64_t session_id = 0;
  EXPECT_TRUE(CreateSession(&handler, &session_id));
  + {
  + // Move to PRECOMPOSITION mode.
  + // On Windows, its initial mode is DIRECT.
  + commands::Command command;
  + commands::Input *input = command.mutable_input();
  + input->set_id(session_id);
  + input->set_type(commands::Input::SEND_KEY);
  + input->mutable_key()->set_special_key(commands::KeyEvent::ON);
  + EXPECT_TRUE(handler.EvalCommand(&command));
  + }
  {
  // KOTOERI doesn't assign anything to ctrl+shift+space (precomposition) so
  // SEND_KEY shouldn't consume it.
  