Improve integer test for random function

[mgreter]

This should fix #1514 ... maybe it is worth a further look as I expected a smaller rounding error to compensate. Also the checks should probably be implemented more generic so others can re-use them.

[am11]

There is probably one related edge case as @chriseppstein described in sass/sass#1819:

a {
  b: (29 / 7 * 7) == 29;
}

should produce:

a {
  b: true; }  /* at present, it generates b: false */

Reminds me of: https://isocpp.org/wiki/faq/newbie#floating-point-arith2 :)

[mgreter]

Also added the epsilon test for number values, so the other sample should now also work. As I said, there are probably more edge cases like this, but this should at least fix the most important ones.

[am11]

Thanks! a45d5c0 fixed the aforementioned edge case for equality. 👍