Adjust indentation of line comments inside expression switches

[copybara-service[bot]]

Adjust indentation of line comments inside expression switches

For statement switches there's some ambiguity about whether a comment documents the previous or next case:

  case 1:
    // case 1 falls through to 2
  case 2:
    doSomething()

  // this is information about case 1
  case 1:
  // this is information about case 2
  case 2:
    doSomething()

For expression switches there is no fall through, so assume that a line comments before a case label always apply to the case label after it.