This reverts commit 6c8aed76.

Reason for revert: Breaks some debug bots:
https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20-%20debug/builds/16754
https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20debug/builds/17654

Original change's description:
> [wasm] Check the size of a function body before storing it
> 
> We stored the size of a function body before we check that
> these values are valid. This caused a failing DCHECK in the constructor
> of WireBytesRef which checked for integer overflows. With this CL we
> check the size of the function body before we create the WireBytesRef.
> 
> R=​clemensh@chromium.org
> 
> Bug: chromium:738097
> Change-Id: I18f8b628c1499aae9c8e9340ea73c87f19e6f1d7
> Reviewed-on: https://chromium-review.googlesource.com/561000
> Commit-Queue: Andreas Haas <ahaas@chromium.org>
> Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#46442}

TBR=ahaas@chromium.org,clemensh@chromium.org

Change-Id: Ifd533c0dee369c746bc97fea13275ebc09ed5eff
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:738097
Reviewed-on: https://chromium-review.googlesource.com/561517Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46445}