Revert of [wasm] Enforce that function bodies end with the \"end\" opcode. (patchset #6 id:100001 of https://codereview.chromium.org/2630553002/ )

Reason for revert:
Still breaks Win64 clang build.

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-Original-Commit-Position: refs/heads/master@{#42286}
> Committed: https://chromium.googlesource.com/v8/v8/+/fcc6e85ec6b01e5367795f98aff104b1ff23f619
> Review-Url: https://codereview.chromium.org/2630553002
> Cr-Commit-Position: refs/heads/master@{#42315}
> Committed: https://chromium.googlesource.com/v8/v8/+/74a2f9b7d3c3d9a9284ab8d5a9d08618b8194966

TBR=mtrofin@chromium.org,rossberg@chromium.org,jbroman@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/2636463002
Cr-Commit-Position: refs/heads/master@{#42317}