Fix rendering of Switch statements

Previously, 
  switch (foo) {
    case 1:
      bar();
      break;
  }
would render as
  switch (foo) {
    case 1: {
      bar();
      break;
    }
  }
and many switch statements rendered with spurious noops.
This fixes that, and makes the switch body getter available on the
ancestor class of both default: and case: statements.

And made sure that a program consisting of only a directive prologue
does not fail to parse.


Submitted @3873

[MikeSamuel, 2009-11-30 22:59:27]

ping

[metaweta, 2009-12-01 00:09:06]

LGTM