“Like Google Mail, Google Docs almost entirely consists of obfuscated JavaScript, some of it common between the two.”
Getting Google Docs to run in a new browser engine took months and more than 30 separate fixes. Ekioh believes Flow is the only engine written after Docs that can run it at all. The web is supposed to be an open standard. In practice it is whatever Chrome happens to do, and anyone building a new browser has to reverse engineer Google’s apps to prove it.