Update engine.Identifier().
Update .Property().
Add quotes for index literal.
Update .Method().
Add quotes if necessary when output literal of failed reference.
Forbid continuous assign expression.
Let property could be left hand of assignment expression.
Method cannot be left hand of assignment expression.
Finish .List().
Update the production of mapItem.
Update.
Update .Map() and .UnaryExpr().
Restore context when finish render.
Update .BinaryExpr().
Finish .If()