The ToBooleanHints were used to represent the ToBoolean feedback
collected by Fullcodegen. But Ignition doesn't collect this feedback
and also TurboFan doesn't make use of the hints, so we should remove
this for now.

Bug: v8:7101
Change-Id: Ifc97d3ebb7494029b33ad79fc8bafdf3c08fb871
Reviewed-on: https://chromium-review.googlesource.com/778163Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49470}