Deletes the now unused Full-codegen compiler. Also removes some macro
assembler instructions which are no longer used.

Note: there is still additional cleanup work to do after this lands
(e.g., remove support for FCG frames support and FCG
debugger support, etc.), but this will be done in followup CLs to keep
this patch managable.

BUG=v8:6409

Change-Id: I8d828fe7a64d29f2c1252d5fda968a630a2e9ef2
Reviewed-on: https://chromium-review.googlesource.com/584773
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47307}