Soon the Boeing 787 Dreamliner won’t be the only carbon composite jetliner carrying passengers, and people in the seats will get a chance to say what they really think. And now that the planes offer internet connectivity in the sky, they can do it in real time on social media. Airbus’ A350 XWB on Thursday started its final round of flight testing, which consists of round-the-world trips to test the plane’s performance in the kind of situations, including at airports, it will encounter in commercial…