Make the RedundancyElimination handle all simplified operators that are
listed in the SIMPLIFIED_CHECKED_OP_LIST, and fix a couple of bugs and
oversights in the code. This also adds a lot of test coverage for all
the cases that we care about in RedundancyElimination (with respect to
Check/Checked simplified operators).

Bug: v8:8015
Change-Id: I57d29113389841b09abcd013313bf5dd1c67735f
Reviewed-on: https://chromium-review.googlesource.com/1233655Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56032}