This is a first testing CL to add tests for mjsunit assertions to the
message tests.

R=clemensh@chromium.org

Bug: v8:7310
Change-Id: Ibbeafebb116f9608c70687f141986ab4534c6b2a
Reviewed-on: https://chromium-review.googlesource.com/803555Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51441}