Toolkit dependency 'early warning' system

gistfile1.html

<!-- bad thing to be avoided -->

<element name="x-foo">
  <script>
    rarelyUsedMethod: function() {
      missingDependency.doWork();
    }
  </script>
</element>

<!-- dependency requisition via custom element -->

<element name="x-foo">
  <script>
    var imports = Toolkit.require('tk-dostuff', 'tk-filter', 'tk-goodies');
    var dostuff = imports.tk_dostuff, filter = imports.tk_filter, goodies = imports.tk_goodies;
    Toolkit.register(this, {
      ready: function() {
        dostuff.doStuff(filter.filter(goodies.emit()));
      }
    });
    Toolkit._require = function(inTag) {
      var elt = document.createElement(inTag);
      if (elt.api) {
        return elt.api;
      } else {
        throw new Error(inTag + ' dependency not avaiable.');
      }
    }
    Toolkit.require = function() {
      var imports = {};
      for (var i=0, a; a=arguments[i]; i++) {
        imports[a] = Toolkit._require(a);
      }
      return imports;
    }
  <script>
</element>