gistfile1.txt

var yourStringBundle = Services.strings.createBundle('chrome://blah@jetpack/content/bootstrap.properties?' + Math.random()); /* Randomize URI to work around bug 719376 */

var props = yourStringBundle.getSimpleEnumeration();
// MDN says getSimpleEnumeration returns nsIPropertyElement // https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsIStringBundle#getSimpleEnumeration%28%29

while (props.hasMoreElements()) {
  var prop = props.getNext();
  // doing console.log(prop) says its an XPCWrappedObject but we see QueryInterface (QI), so let's try QI'ing to nsiPropertyElement

  var propEl = prop.QueryInterface(Ci.nsIPropertyElement);
  // doing console.log(propEl) shows the object has some fields that interest us

  var key = propEl.key;
  var str = propEl.value;
  
  console.info(key, str); // there you go
}

del