Loop unrolling did not work properly with floating control. Seeing as
very few spots in the wasm compiler introduced floating control, we
decided to disallow it altogether.
Changes:
- When lowering 64-bit rol/ror/clz/ctz in 32-bit platforms, we use a
  diamond operator, which used to introduce floating control. This CL
  adds a control edge to these operators so that the diamond can be
  chained to that control instead.
- During loop analysis, as an additional safety check, we check that the
  explored loop does not have floating control. Exceptionally, floating
  control pointing directly do start() is allowed.
- Change wasm-compiler so that generated floating projections point to
  start() even after stack check patch-in.

Bug: chromium:1184929, v8:11298
Change-Id: I1ee063f5250037ae6c84d2f16b0bd8fff3923117
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2876851Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74527}