Consider supporting stringref strings #41
Description
Chrome has supported stringref via --wasm-staging/enable-experimental-webassembly-features since 2023 (and hopefully they won't remove it too soon); it may be worth investigating performance benefits of emitting stringref instructions rather than externref, especially as we can't take advantage of most JS string builtin functions due to scratch quirks.
Binaryen also supports its own form of stringref, for optimisation, so it may turn out to be beneficial for wasm-opt (const folding in particular) for us to emit stringref. (I am not clear if it is possible for binaryen to emit stringref, or if it always lowers to js-string-builtins).
It may be that #42 means that any const-folding opportunities offered by emitting stringref are nullified.