* Implement getter/setter with computed value
* Fix parsing getter/setter after static or generator token
* Allow storing expressions in AST_SymbolMethod
- Partially reverting 91cdb93e57 and eaf3911c31 and reimplement
- Add generators support for objects and classes
- Only classes can have static methods so restrict use of it
Special thanks to @rvanvelzen and @kzc for reviewing this patch and
providing constructive feedback over and over again.