[IR] Tweaks/fixes to explicit binding handling opts.

* Eliminates expensive analysis in situations where bindings dont
  escape, inlines binding into local scope, and eliminates push/pop
  of bindings.

  Currently, this doesn't deal with aliasing based access of
  bindings in certain situations like Module.nesting which is an
  artificial dependency since that method really requires access to
  the ir/static-scope, not necessarily the binding. But currently,
  access to ir/static-scope goes through the binding.