Improve memory usage in redefer parse scenario

Redefer parse feature helps in freeing function bodies and getting back the memory. From my experiment on identifying memory usage in `chakracore`, below are 2 things that we should do in order to get more benefit out of redefer parse.
* Perform defer parsing for lambdas, getters and setters
* Ignore `CanDeferParse` flag when trying to redefer. For this to happen above, WI need to be done.