Didn't know that people still use Netbeans, but Netbeans doesn't support ES6 syntax yet, but it might be close according to one of the comments:
Guys, I have to apologise. The parser based on Antlr doesn't suffer from performance problems like a month ago, but the memory consumption is still high. We run in problems in ANTLR 4 runtime itself and we are working with antlr authors to solving these issues. I can not guess what time it will take.
In parallel I have taken a close source parser and currently I'm trying to work with this one. Unfortunately it's close source and we have to go through licensing process, where I don't have any doubts how it long it can take. When I get the permission to put the parser to our hg, then there will be available build and hopefully with a few implemented ECMA 6 features.