If objectGroup is console we should correctly save last evaluated result to expose for next console call in $_ variable.

R=dgozman@chromium.org

Bug: none
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ie0ba2d302606b1c9f096a9a3a107a51a80556c49
Reviewed-on: https://chromium-review.googlesource.com/598936Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47097}