Most parallel moves do not actually require the heavy analysis in the
GapResolver since there is no overlap between source and destination
registers. Handle some of these cases by a fast-path to avoid the
quadratic behaviour in the general case.
The fast path is taken for about 2/3 of the non-empty parallel moves on
wasm workloads.

R=herhut@chromium.org, titzer@chromium.org

Bug: v8:8423
Change-Id: I026256fd6cf268f176fccc97f0f427e07629aeb3
Reviewed-on: https://chromium-review.googlesource.com/c/1400410
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Stephan Herhut <herhut@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58644}