Check that a v128 imported global in a Wasm module is initialized with a
WebAssembly.Global object.

This is technically impossible, because creating WebAssembly.Global of
type v128 is an error, and creating one of any other type is a type
mismatch. However, we still need this check to avoid hitting an
unreachable case when setting the value of the global later on.

Also, this is not a validation error, since the v128 restriction is only
a Web/JS limitation. Other embedders can choose to do something
different with this module with an imported v128 global.

Bug: chromium:1127740
Change-Id: I6d444578c082b6b1c353cfa2fd82bb42eb14fc3b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2410659Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69919}