Auto-transform reserved words to be quoted in non-es5 mode:

1. Class methods uses a computed member expression on the prototype when the method name is a reserved word
2. Destructering would use a computed member expression when the key to pull is a reserved word
3. Object concise method will qoute the identifier (i.e. make it a string literal) when it's a reserved words
4. reserved-word-visitor is a default visitor in non-es5 mode that would handles everything else:
  a. Handles properties in object expressions
  b. Handles member expressions
Also no strong preference. But don't want to spend too much time on this (we have the transform in Recast and this is super temporary)