This CL replaces the JavaScript fall-back for Array.p.shift with a
baseline C++ implementation.

R=jgruber@chromium.org

Bug: v8:7624
Change-Id: Ib55e04e18e4e69089fc541636d3cad7fcb4c7245
Reviewed-on: https://chromium-review.googlesource.com/1186327
Commit-Queue: Simon Zünd <szuend@google.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55576}