This is the counterpart of https://crrev.com/c/822471.
It implements asm.js bounds checks for loads using normal branch nodes
and removes the need for CheckedLoad, improving maintainability at some
small cost to compilation time.

R=ahaas@chromium.org
CC=mstarzinger@chromium.org, titzer@chromium.org

Change-Id: I7a2716f364b9e4d7beb9cc460eb028c3bd1c3a99
Reviewed-on: https://chromium-review.googlesource.com/832457
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50192}