Added registers and conditions for this architecture.
Implemented some of the instructions, mainly for wasm
context operations.

Bug: v8:6600
Change-Id: I5f3e32eb4d284172b21434456395256872da3b46
Reviewed-on: https://chromium-review.googlesource.com/906609
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51176}