When an instance of a constructor goes dictionary mode, this changes the initial map
of that constructor to also be in dictionary mode. This avoids spurious hidden class
creation, that also results in IC misses.

BUG=

Change-Id: I0e70f822ac345d0224f2092ec473621a603d4cc5
Reviewed-on: https://chromium-review.googlesource.com/446361Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43452}