This reverts commit 03d5a7ba.

Reason for revert: Needs rebaseline:
https://ci.chromium.org/p/v8/builders/ci/V8%20Blink%20Linux/3243

Original change's description:
> [wasm] The name of a custom section can cause a validation error
> 
> The WebAssembly spec defines that the name of a custom section can cause
> a validation error. The streaming decoder, however, used a separate
> Decoder object to decode the name, and thereby avoided a validation
> error. With this CL the streaming decoder uses the main decoder to
> decode the name of the custom section.
> 
> In addition this CL removes the test mjsunit/regress/wasm/regress-789952.
> This test defined an invalid WebAssembly module and expected it to
> compile. As it is a regression test, it makes no sense to fix the test.
> The module is invalid because it defines the length of the custom section
> to be '0', so there are no bytes in the custom section for its name.
> 
> R=​clemensb@chromium.org
> CC=​thibaudm@chromium.org
> 
> Bug: v8:10126
> Change-Id: I8cfc77c9a5916570d5362d5922e0179a29774da8
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2041446
> Commit-Queue: Andreas Haas <ahaas@chromium.org>
> Reviewed-by: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#66348}

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

Change-Id: I5a7ea265ce47b9e685a5056bb83db6dc58f774a9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:10126
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2065168Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66356}