this breaks libsass.scss

$four: "4";
$seven: "7";
$pi: 3.14159;
$phi: 1.618;
$null: null;

@if $seven > $four { // may only compare numbers on line 2 at column 9
  .fourIsBiggerThanSeven {
    color: green;
  }
}


@if $pi > $phi {
  .piIsBiggerThanPhi {
    color: green;
  }
}

@if $four > null {
  .fourIsBiggerThanNull {
    color: green;
  }
}