What benefit do you expect your "machine code" to have over JavaScript?All the benefits that people proposing new web languages would impart. There are a good reasons why Google are proposing running Dart straight on their VM in Chrome. It will be faster, safer, easier to jit, easier to prove correct etc. Having a firm foundation would make it easier to innovate. Companies could still be encouraged to compete for faster and safer implementations.
The failure of Parrot to catch on has very little to do with the technology, nor the proposition of a general-purpose dynamic language VM. Parrot was simply in the wrong place at the wrong time (and it took too long to deliver). It also made the mistake of tying itself to an unfinished language spec. If they had concentrated on making a VM that could run Python, Ruby and Javascript they would have been in the right place at the right time when Perl 6 was finally ready to be implemented.
People are beginning to use Javascript and the V8 engine in a manner similar to the original Parrot proposal.
The time is right for a general-purpose IL so we can compile Coffeescript straight to the Javascript VM.
LLVM is being questioned by some because a) it isn't a VM it's just an IL so it is a compiler technology not a VM tech b) it is too low level to make the jitting of dynamic languages suitably efficient. LLVM is too low-level; Javascript is too high (and opinionated).
Judging innovation by precedence is always a bad idea.