Why does _evalUrl() use async:false? Would it ever make sense for it to
use async: true? Does it affect the user experience at all?
My guess is that by doing it synchronously rather than async, you
guarantee that javascript files are loaded and executed in order. Is
that the reason?
A common question when using jQuery is: Why am I seeing this
warning: "Synchronous XMLHttpRequest on the main thread... jquery.js?body=1:9628"?
The answer is that they are inserting a new <script> tag to
the HTML via jQuery, and then jQuery loads the external script file
src synchronously.