Code size reduction opportunity: bring back .bind calls

[NTillmann]

#2577 disables the generation of .bind calls; instead, that changes makes Prepack always generate full-blown wrapper functions.

Bring back the original functionality, or explore other ways to bind local environments to functions which may be possible for mobile.

It's interesting that #2577 also didn't make any tests fail. So part of the work should be to produce test cases for all of the different conditions currently considered in #2577.