Again, modules in ES6 started before Dart ("Dash") leaked.
Your original comment said "Thank you Dart for showing us the way." Happy-clappy nonsense!
Why am I on the warpath?
First, sloppy history retelling -- even if just fannish exaggeration -- is bad in itself.
Second, and I've gone on the record about this since 2011, Google chose the wrong "REPLACE JS BECAUSE IT CANNOT BE FIXED" strategy, and wasted years and megabucks. Their choice, but not something to congratulate them over. We could have had even more in ES6 if the V8 team had not been reset and JS back-benched as it was. That cost years.
Third, the meme you're spreading is that JS is incompetent or severely hobbled without being shown the way by enlightened others. This does a disservice to many people including the V8 team (the new team) members working in earnest on JS via implementations and TC39. It's a particular falsehood to which I object as a peer of those people on TC39.
Dart as an intentionally designed, full-time-job-for-60+-people, good and well-done project at Google, creating useful and coherent tools as well as the language itself? A fine thing in isolation, ignoring the actual history, global strategy, and consequent trade-offs.
Dart as the thing that showed JS the way (same for CoffeeScript, but let's defer that and focus on Dart)? A fraudulent claim that covers up real mistakes in strategy made by Google, which cost big time and money, not just for JS and the Web, but bad also (in light of this week's news) for Dart.
Why was the strategy bad for Dart? One example: only now, finally, might bignums get into ES7/2016. They could have been in ES6 and in V8 and other engines by now, since we were working on them since 2010, but without a champion who saw the priority and paid someone to spec and implement them in V8.
Do you see my point? Please do not play games about me "admitting" SIMD and maybe one other something else came from Dart. I've written that many times in multiple threads without prodding, on HN and on twitter. This is not an ego match. It's about accurate attribution of history, work, influence, and causality.