Fixes#5323. Previously we added space after `/*` _on the first line
only,_ but the intent is to only fix the indentation of comments, not
changing their "contents". Besides, this was inconsistent with the
handling of every following line. Finally, it broke `/*!` comments which
some minifiers look for to know which (license) comments to keep.
People can use https://eslint.org/docs/rules/spaced-comment to enforce
when to start comments with spaces.