The validate-asm flag now implies lazy compilation.

R=titzer@chromium.org, ahaas@chromium.org
BUG=v8:5991

Change-Id: I00fb5ddbe13440941a3fafd9175cc9a5d182e15a
Reviewed-on: https://chromium-review.googlesource.com/451318
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Brad Nelson <bradnelson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43952}