After poking around I wrote a patch (attached). Worth noting though, for
some reason it doesn't work for ternary without starting colon, e.g.:

    const a = cond1 ? 1 :
      cond2 ? 2 :
      cond3 ? 3 : 4;

I'm unclear why, per my understanding the "standalone-parent" of the
whole ternary chain (disregarding where the point is) is the `const a
=` declaration.

Such bug also persists in c++-ts-mode (as opposed to non-ts plain c++-
mode). I'm not sure if it's me misunderstanding something or not…