Correctness pass

[Shfty]

• Correct behavior for combine functions
  • Appears to be evaluating everything, then returning an out-of-date context
• Improve IR
  • Merge consecutive Emit statements
  • Prevent unnecessary intermediary bindings
  • Prevent automatic zero-initialization
• Respect naga arithmetic rules
  • Limited vector-float operations
  • ex. No Vec* / f32 allowed

[Shfty]

Done: Now able to generate validation-passing IR with correct behaviour.