WASM support

[flupke]

I get this error when trying to build for wasm:

   Compiling async-broadcast v0.7.1
error[E0599]: no method named `wait` found for struct `SendInner` in the current scope
    --> /home/flupke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/async-broadcast-0.7.1/src/lib.rs:1647:1
     |
1647 | / easy_wrapper! {
1648 | |     /// A future returned by [`Sender::broadcast()`].
1649 | |     #[derive(Debug)]
1650 | |     #[must_use = "futures do nothing unless .awaited"]
1651 | |     pub struct Send<'a, T: Clone>(SendInner<'a, T> => Result<Option<T>, SendError<T>>);
1652 | |     pub(crate) wait();
1653 | | }
     | |_^ method not found in `SendInner<'_, T>`
1654 |
1655 | / pin_project! {
1656 | |     #[derive(Debug)]
1657 | |     struct SendInner<'a, T> {
1658 | |         sender: &'a Sender<T>,
...    |
1665 | |     }
1666 | | }
     | |_- method `wait` not found for this struct
     |
     = help: items from traits can only be used if the trait is implemented and in scope
     = note: the following trait defines an item `wait`, perhaps you need to implement it:
             candidate #1: `Strategy`
     = note: this error originates in the macro `easy_wrapper` (in Nightly builds, run with -Z macro-backtrace for more info)

which is caused by this in the event-listener-strategy crate:

    /// Wait for the future to complete, blocking the current thread.
    ///
    /// This function uses the [`Blocking`] strategy to poll the future until it is ready.
    ///
    /// The future should only return `Pending` if `Strategy::poll` returns error. Otherwise,
    /// this function polls the future in a hot loop.
    #[cfg(all(feature = "std", not(target_family = "wasm")))]
    #[cfg_attr(docsrs, doc(all(feature = "std", not(target_family = "wasm"))))]
    fn wait(mut self) -> Self::Output
    where
        Self: Sized,
    {
        // SAFETY: `self`/`this` is not moved out after this.
        let mut this = unsafe { Pin::new_unchecked(&mut self) };

        loop {
            if let Poll::Ready(res) = this
                .as_mut()
                .poll_with_strategy(&mut Blocking::default(), &mut ())
            {
                return res;
            }
        }
    }

Do you think it would be possible to add WASM support behind a feature flag, or is this fundamentally needed?