Use the new macro to define lazily initialized leaky singletons. Avoid
the clumsy LazyInstance, which we can hopefully remove soon.

R=mlippautz@chromium.org

Bug: v8:8600
Change-Id: Ib4d23f275c7ff5ca71fa9b47345284935330ead7
Reviewed-on: https://chromium-review.googlesource.com/c/1397711Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58594}