This adds support for materializing objects of {JSGeneratorObject} type
during deoptimization. Cases where soft-deopts remove any escaping use
of the implicit generator object can cause it to be escape analyzed.

R=jarin@chromium.org
TEST=mjsunit/regress/regress-crbug-732169
BUG=chromium:732169

Change-Id: I2ec10b2a509a4f37a456a8ca2fd74b8de2fb55be
Reviewed-on: https://chromium-review.googlesource.com/530847Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45849}