Use sparingly!
This doesn't add any really new functionality, other than making it more
convenient to do this.
This will primarily be used to wrap a WasmModule to be referenced from a
JSObject that represents an instance. There is one WasmModule C++ object
per parsed WasmModule, so this should not be more than a handful or a few
dozen in well-behaved programs.
R=rossberg@chromium.org,mlippautz@chromium.org
BUG=
Review-Url: https://codereview.chromium.org/2409173005
Cr-Commit-Position: refs/heads/master@{#40346}
