Why not just make the API magically more like the way I want to write things.

firefoxdespire.js

var workers = [];
PageMod({
  include: "*",
  contentScriptWhen: 'end',
  contentScriptFile: data.url("content.js"),
  attachTo: ["top", "existing"],
  onAttach: function(worker) {
    workers.push(worker);
    worker.on('detach', function () {
        log('worker detach');
        detachWorker(this, workers);
    });
  }
)};

function detachWorker(worker, workerArray) {
  var index = workerArray.indexOf(worker);
  if(index != -1) {
    workerArray.splice(index, 1);
  }
}

function getWorker(tab, workerArray) {
  var _;
  function isTab(worker) {
    if (worker.tab === tab) _ = worker;
  }
  workerArray.forEach(isTab);
  return _;
}

function emitMessage(worker, eventName, eventData){
  var message = {
    id: Math.random(),
    name: eventName,
    detail: eventData
  };
  worker.postMessage(message);
}