Function normalize_and_determine_support 

fn normalize_and_determine_support<T: Operation>(
    cx: &mut JSContext,
    op: &str,
    algorithm: &AlgorithmIdentifier,
    length: Option<u32>,
) -> bool

Helper function for Step 4 - 6 of https://wicg.github.io/webcrypto-modern-algos/#dfn-check-support-for-algorithm