This CL also removes LoadICProtoArray* builtins which are no longer necessary.

Bug: v8:7206, v8:5561
Change-Id: Ic5d9a3d4d21c4bd5e5e1cd110bd029ced157a000
Reviewed-on: https://chromium-review.googlesource.com/819252
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50104}