Implement basic JIT

For example, this is the output for *Hashtable::put*: https://gist.github.com/marco-c/9920ca772b8421d8330d
One way to refactor this would be to just throw an exception in resolve and let resolve callers catch the exception and call raiseExceptionAndYield.
The downside is that this would increase the size of VM.execute and would probably also slow it down because of the try catches.

Do you have other refactoring ideas?