Revert of [wasm] Enforce that function bodies end with the \"end\" opcode. (patchset #3 id:40001 of https://codereview.chromium.org/2630553002/ )

Reason for revert:
Caused tree to close by failing compilation:

https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20clang/builds/4451

Original issue's description:
> [wasm] Enforce that function bodies end with the \"end\" opcode.
>
> R=rossberg@chromium.org
> BUG=chromium:575167
>
> Review-Url: https://codereview.chromium.org/2630553002
> Cr-Commit-Position: refs/heads/master@{#42286}
> Committed: https://chromium.googlesource.com/v8/v8/+/fcc6e85ec6b01e5367795f98aff104b1ff23f619

TBR=mtrofin@chromium.org,rossberg@chromium.org,jbroman@chromium.org,titzer@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:575167

Review-Url: https://codereview.chromium.org/2628883006
Cr-Commit-Position: refs/heads/master@{#42287}