Baseline compiler

[indutny]

I think we should do a baseline compilation for a large portion of javascript code instead of creating SSA and allocating registers.

The idea is (at least in my head) to generate CFG using ssa.js and perform some alternative register allocation algorithm on it, thus skipping the SSA transformation and Linearscan.

The register allocation could just assign rax, rbx, rcx ... to inputs and spill everything else right after the instruction. Should work just fine for the compilation speed reasons.