trying to add `require()` to Web Workers

gistfile1.js

// this works, but the imported scripts pollute the global namespace
function require(url) {
  self.module = { exports:{} };
  importScripts(url);
  var exports = self.module.exports;
  delete self.module;
  return exports;
};

// this is the one I want:
function require(url) {
  var timeout = 15 * 1000; // 15s for now
  var promise = local.http.dispatch({ method:'get', url:url });
  var startTime = (new Date()).getTime();
  while (promise.isUnfulfilled() && ((new Date()).getTime() - startTime) < timeout) {
    // :TODO: let message queue drain?
  }
  if (promise.isFulfilled()) {
    var res = promise.value;
    if (/javascript/.test(res.headers['content-type']) || /\.js$/.test(url)) {
      var module = { exports:{} };
      importScripts(makeJSDataURI('(function(){ ' + dataUrl + ' })();'));
      return module.exports;
    } else
      return res.body;
  }
  return null;
}