That way, we will know if it was able to get the fast or slow memory and we won't have to compile code twice. Obviously there are still some cases where we have to compile code twice, but this will allow us to only compile once for the single Module single Intance use case (and probably others). When we instantiate, we'll just have to be aware that we may have already created a Wasm::Memory
*** This bug has been marked as a duplicate of bug 170628 ***