credit.md

After Ryosuke, Travis, Wilson, William, and I discussed the problem for an hour over a burrito, William came up with this approach. All hail William.

select.js

var shadow = host.createShadowRoot({ mode: 'closed' });

// Fill the shadow-root
shadow.innerHTML = template;

// Define the distribution logic. It's important
// that this isn't tied to creation to make it
// possible for  a sub-class to override 
shadow.distribution = candidates => {
  var points = shadow.querySelectorAll('content');
  candidates.forEach(candidate => {
    for (var i = 0; i < points.length; i++) {
      var selector = points[i].getAttribute('select');
      if (!selector || candidate.matches(selector)) {
        points[i].add(candidate);
        break;
      }
    });
  });
};

// Run initial distribution
shadow.distribute();

// Attach mutation observer that invokes distribute() on childList changes

shadow.webidl

TODO