This issue was originally filed by @tatumizer

BEFORE:
main() {
  var zero = 0;
  if (0 == 0) {
    zero=0;
  } else if (0 == 1) {
    zero=1;
  } else if (0 == 2) {
    zero =2;
  }
  print(0);
}
AFTER:
main() {
  var zero = 0;
  if (0 == 0) {
    zero = 0;
  } else {
    if (0 == 1) {
      zero = 1;
    } else {
      if (0 == 2) {
        zero = 2;
      }
    }
  }
  print(0);
}

A lot of unnecessary "{}" inserted. Apparently, formatter doesn't think of "else if" as a valid construct, but it is.
Note it's not the same problem as orphans as per issue #16847.
In the latest dev release, orphans produce the same output as above, that is
foo() {
  var zero = 0;
  if (0 == 0)
    zero=0;
  else if (0 == 1)
    zero=1;
  else if (0 == 2)
    zero =2;
 
  print(0);
}
is now formatted exactly as in AFTER section above, inserting unnecessary {}. Whereas it was supposed to insert minimal amount of {}, so that the thing after formatting should look as in BEFORE example above.

Another small issue: I had to insert print(0) in the end; without it, formatter prints red error message at the bottom: expected EOF but got '}'