Fix _str() for PrintAST, PrintXAST and ReturnAST.
Fix _str() for PrintAST, PrintXAST and ReturnAST.

doerwalter/LivingLogic.Javascript.ul4,LivingLogic/LivingLogic.Javascript.ul4,LivingLogic/LivingLogic.Javascript.ul4,doerwalter/LivingLogic.Javascript.ul4