Prettier 1.15.1
Playground link

--parser babylon
--no-semi

Input:

const foo = 123
// Nothing to see here.
;["2", "3"].forEach(x => console.log(x))

Output:

const foo = 123
  // Nothing to see here.
;["2", "3"].forEach(x => console.log(x))

Expected behavior:

const foo = 123
// Nothing to see here.
;["2", "3"].forEach(x => console.log(x))

This worked as expected in 1.14.3 and is a new issue in 1.15.1:
https://github.com/badges/shields/pull/2289/files#diff-676bb6a761a788e31078b1ca347c3e63

Apologies if this has already been reported! There are some related issues around semicolons and comments including #5022 but they are older and seem to be different from this one.