WIP computed properties
switch to a system where bound functions are invoked through a wrapper, so we can easily directly invoke any function in llvm ir.
we pass this with new esprima
property account for computed property keys when calculating free variables
correct builtin prototypes so we pass tostring5.js
set esprima to tolerant mode.  we detect many of the same errors, but we want to give more error/warning output, not fail to parse the entire file
we don't need this switch BB