Non-empty loops being collapsed if first node is EmptyStatement

[jbt]

e.g. while (a) { ; b(); } -> while(a);; (link)

I tried making some test-cases + fixing up the check for empty nodes by checking over every descendent node rather than just the first, but my do-while case is failing completely for magic-string reasons I don't fully understand.

Additionally, all cases where a curly-braced loop could be reduced to a single-statement body aren't working because I can't figure out how to trim leading/trailing EmptyStatements.

Incidentally it looks like there's a few more cases where leading empty statements in a block change the output (e.g. if (a) { b(); } vs if (a) { ; b(); }) but the loops are the only case where it's doing something it definitely shouldn't.

[Rich-Harris]

Thanks. It was operating under the incorrect assumption that if the first statement of the body was an EmptyStatement, the body itself was empty. It should really remove empty statements altogether — will get to that soon — but #59 generates correct if suboptimal code