This class used to be based on DispatchTable, which itself uses an
interval tree to both categorize and canonicalize ranges
(i.e. such that no overlap and all immediately adjacent ranges are
merged). The produced ranges were then entered into lists for
{bmp,lead_surrogate,trail_surrogate,non_bmp} splits.

With this CL, we simplify to a plain loop over all character range
kinds instead. The dispatch table (and ZoneSplayList, perhaps
SplayList) can be removed in follow-ups.

Bug: v8:9359
Change-Id: I9c6b72f3bc44d1557af7c74419709ae5662611f1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1664053
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62260}