Revert of [refactoring] Split CodeAssemblerState out of CodeAssembler (patchset #8 id:140001 of https://codereview.chromium.org/2498073002/ )

Reason for revert:
https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20shared doesn't want to compile. Missing export annotation?

Original issue's description:
> [refactoring] Split CodeAssemblerState out of CodeAssembler
>
> This is in preparation for introducing more specialized
> CodeStubAssembler subclasses. The state object can be handed
> around, while the Assembler instances are temporary-scoped.
>
> BUG=v8:5628

TBR=ishell@chromium.org,mstarzinger@chromium.org,jkummerow@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5628

Review-Url: https://codereview.chromium.org/2504913002
Cr-Commit-Position: refs/heads/master@{#41018}