Load mjsunit.js inside the realm as otherwise the functions are not
available in the realm's scope.

This also prints timestamps after each test to easier track down slow
tests.

We also pass --omit-quit to not stop too early.

This also adds the ability to skip certain tests for endurance
fuzzing and skips some tests with known problems.

TBR=ulan@chromium.org,hpayer@chromium.org

Bug: v8:6972, v8:7400
Change-Id: I44464c28bfb10c84f2e59972e7b86945a47ca3b3
Reviewed-on: https://chromium-review.googlesource.com/899008Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51066}