Similar to the Scavenger, the Minor MC updates typed pointers into the
young generation and thus requires priviliges to write to code space.

Bug: chromium:651354
Change-Id: If5ce600f651ccb04b6ac3d82e6c2e311bfd7dc4d
Reviewed-on: https://chromium-review.googlesource.com/809013Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49884}