dillon1000/react

Improve validateNoRefAccessInRender

Rewrites the validation to not rely on the mutable range of functions to 
determine whether they are called or not, since the range can be extended for 
other reasons (they happen to reference a mutable value that is mutated later, 
even though the function isn't called during render). 

Instead we use the same approach as validateNoSetStateInRender, explicitly 
tracking references to function expressions that access refs, and checking if 
those function expressions appear to be called. This can have false negatives, 
as with the setState validation, but catches lots of obviously incorrect code 
without false positives.