As part of https://bugs.webkit.org/show_bug.cgi?id=187373, when emitting an op_get_by_bal within an IndexedForInContext we force it to be emitted as a wide instruction since we might need to patch the instruction later and we want to guarantee that the alternative value fits in the instruction stream. However, we know the only value that we might use to patch the instruction ahead of time, so we could do do a Fits::check to see if it would fit in a narrow instruction and only force it to be wide otherwise.