Use the new transforms to try and simplify loops into for-loops.
Emit loops when the initialiser, condition and continuing are simple enough to do so.
Bug: tint:952
Change-Id: I5b3c225b245ffa72996abf6a70f52a9cd25b748e
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/56772
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>
Ben Clayton