Create an executeMultipleFrames()

[torch2424]

This is for frameskip and avoid more jumps from Js to Wasm

[torch2424]

May want to close this, since calls to wasm are fast now: https://hacks.mozilla.org/2018/10/calls-between-javascript-and-webassembly-are-finally-fast-%F0%9F%8E%89/

I assume all browsers would follow suit soon.