SE-0257: Eliding commas from multiline expression lists

[masters3d]

@TellowKrinkle

Would you mind adding a reason for the -1 ? AFAIK the goal of these proposal reviews is not a vote on the feature (the final decision is made by the core swift team, not by whatever gets the most votes), but to offer reasons why you think this is a good or bad idea for the core swift team to consider. If your reason was already mentioned, just poke the button under it, no need to make a whole new post.

@John_McCall

I'd like to encourage people who do have an opinion about a proposal to always write at least some formal feedback on it; even something as basic as a "+1" in the review thread provides a much clearer signal than, say, clicking on the review post, or only commenting in the thread to try to answer objections raised by other people's reviews.

Probably need to discuss this on another tread