Memory leaks into JS Binding

Seams that JS class binding finalizer never gets called, IE: XmlHTTPRequest never calls basic_object_finalize even when object gets out of scope in JS.

Probably you should apply this rules of handling object for correct GC:
https://developer.mozilla.org/en-US/docs/SpiderMonkey/GC_Rooting_Guide

I also notice some memory leak
not only place, a lot,

for chipmunk, this is obvious. even worse, chipmunkā€™s free method is not exposed.
I modified the destroy method for every cp object in js-binds and replace destroy by free method.

Show me. Thanks in advance.