Move dead bytecode elimination from a seperate bytecode pipeline optimizer
into the BytecodeArrayWriter. This removes the last bytecode pipeline
optimizer, which means we can remove the Bytecode pipeline which,
which should increase compile speed.

BUG=v8:6194

Change-Id: I47fb3c3463b2b8a92e02cf7a6b608683fcfa5261
Reviewed-on: https://chromium-review.googlesource.com/471407
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44568}