Currently x instanceof Map/Set checks cannot take the fast path, since
the Map/Set constructor has dictionary properties. To avoid that, just
forcibly migrate the Map/Set constructor to fast properties again once
it's fully setup in the bootstrapper.

Bug: v8:5717, v8:5902
Change-Id: I23dfd00456c9206a0ca5af71dfbc9236982936fc
Reviewed-on: https://chromium-review.googlesource.com/520578
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45663}