Don't change alignment of // comments on consecutive rows

[kwalrath]

The formatter wants each // comment to start one space after the end of the line, but often comments are more readable if they're aligned. Would it be possible to detect when comments are aligned and continue to keep them aligned?

Input:

  assert(v.x == 2 && v.y == 3);         // v   == (2,3)
  assert((v+w).x == 4 && (v+w).y == 5); // v+w == (4,5)
  assert((v-w).x == 0 && (v-w).y == 1); // v-w == (0,1)

Output:

  assert(v.x == 2 && v.y == 3); // v   == (2,3)
  assert((v + w).x == 4 && (v + w).y == 5); // v+w == (4,5)
  assert((v - w).x == 0 && (v - w).y == 1); // v-w == (0,1)

Ideal:

  assert(v.x == 2 && v.y == 3);             // v   == (2,3)
  assert((v + w).x == 4 && (v + w).y == 5); // v+w == (4,5)
  assert((v - w).x == 0 && (v - w).y == 1); // v-w == (0,1)

This code is from https://github.com/dart-lang/dart-up-and-running-book/blob/master/code/ch02/vector.dart (part of a test for a snippet in Chapter 2).

[munificent]

I don't currently have plans to do this, but I agree it is nice in some cases. I'll leave this open as an enhancement.