By now we no longer emit calls with {RelocInfo::CODE_TARGET} as part of
WebAssembly code. Hence the requirement to block sharing of code targets
disappeared and the support can be dropped.

R=jarin@chromium.org

Change-Id: I6df026cd05769ddaa6ea8df5a7b17b62e8a7c373
Reviewed-on: https://chromium-review.googlesource.com/1100889Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53782}