This reverts commit 1cc93be0.

Reason for revert: http://crbug.com/769976

Original change's description:
> [arm64] Add slot copier to masm and use in builtins
> 
> Abstract some stack slot copies through a macro assembler function. This
> eliminates some non-paired stack operations.
> 
> Bug: v8:6644
> Change-Id: Icaa3ebb1bec42587ad461bd548a4225c7b4e5d15
> Reviewed-on: https://chromium-review.googlesource.com/685238
> Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
> Commit-Queue: Martyn Capewell <martyn.capewell@arm.com>
> Cr-Commit-Position: refs/heads/master@{#48177}

TBR=rmcilroy@chromium.org,martyn.capewell@arm.com,bmeurer@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: v8:6644
Change-Id: I9044df7c2be028748d85b7007008331a2aa8173f
Reviewed-on: https://chromium-review.googlesource.com/691874
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48234}