Please, support easy AST generation

[Askar Safin]

Hi. Often the only thing I want to do in Bison is just generate AST and nothing 
else. Unfortunately, in this case code becomes very repetitive. For example, 
this is Bison input I used to generate AST for small JavaScript subset: 
https://zerobin.net/?b9af68c9aa7a31a9#JB4wZseYTq9aKfZOwwZrDqBNCqlEZRj/+DM9bKdgtKU=
 . Please, support some feature, which eliminates the need to write such 
repetitive code. Such code can be easily generated from grammar alone

==
Askar Safin
http://vk.com/safinaskar