Such the VM is way too complicated, and has other problems. (Also, it is difficult to sufficiently control the features of JavaScript programs (not only HTML re

Such the VM is way too complicated, and has other problems. (Also, it is difficult to sufficiently control the features of JavaScript programs (not only HTML related stuff, but also Date and endianness), or to replace specific scripts.) But just if you want a Turing complete language that is incapable of fingerprinting the host environment, there is TeX, which might be incapable of fingerprinting if a bug it has is fixed, and the file I/O is made more restricted. Also, for internet stuff there are many other programs and protocols, so could be used, e.g. SMTP, NNTP, Gopher, Telnet/SSH, etc. (In many ways it will even work better. No need to deal with complex user interfaces that do not even work properly and which is not even the user's intentions.) There is also Glulx, and other VMs, and I also thought of idea to make up a VM for this purpose, too.