This regresses the test case of `zig fmt` deleting empty line comments.
Two open questions here:

 * What should the rules be about deleting empty line comments?
   It makes sense usually, but for array initization, empty line
   comments cause a line break, affecting the row/column alignment.
   Perhaps we should therefore respect all empty line comments?
   Or should we special case array initializations?

 * If we decide to special case some kinds of line comments to respect
   them (which is status quo!), how should that be implemented?