Empty Array literals are amongst the most commonly used literal types on our
top25 page list. Using a custom bytecode we can drop the boilerplate for empty
Array literals alltogether. However, we still need a proper AllocationSite to
track ElementsKind transitions.

Bug: v8:6211, chromium:746935
Change-Id: I891eaa778e4e81e138e483a65f04ae00ae30bd28
Reviewed-on: https://chromium-review.googlesource.com/580932Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46875}