This implements the br_table instruction in LiftoffCompiler by emitting
a binary search tree.

R=titzer@chromium.org

Bug: v8:6600
Change-Id: I89c11501dd3a41556d2fab68af1afbe8c4855d36
Reviewed-on: https://chromium-review.googlesource.com/921641
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51368}