It is perfectly legitimate to create and/or use a method named `define`
in JS outside of RequireJS.
Unfortunately our requirejs.php wrapper is dumb and does not understand
this.
In the long term we need to stop doing this at all. We really should be
able to already, but every time I try to something prevents it.
In the interim, this change adds a secondary check to see if there is an
existing define which _does_ have the right name in it already.
Misha Golenkov