Valued at $45 billion, Bytedance is not most people’s idea of a start-up, and could soon join Alibaba, Baidu and Tencent in the league of Chinese high-tech giants. But it is still a start-up by many definitions, at least until the IPO the company is widely rumored to be preparing for – having just launched a sleek and expansive new web site in several languages. Increasingly, it seems that the giant web platforms are going to play very central roles in the way that consumers interact with the IoT. In the West, Google and Facebook seem completely entrenched. In China, Tencent and Baidu are comparable, but the Chinese market is being shaken up by a new entrant that could dethrone…