zk calls callback functions added by zk.afterLoad() in a different order when embedding a zul

Steps to Reproduce

1. run the zul, check developer tool > Console tab
2. embed the zul from an HTML page (based on zkembedded-app)
3. compare the loading order of 2 cases (not embedded, embedded)

Current Result

• embedded zul
  when zk calls a callback afterLoad('zk'), actually all package wpd files are already loaded.

Expected Result

either we can make the behavior consistent or document it

Debug Information

• since zk embed API puts the callback js (listener.js) at the end of the page. zk embed API ignores script directive, so there is no way to load the script earlier.
  
  But loading zul in a normal way (not-embedded), zk generates the script tag on the expected position we specified in a zul.