Description:
------------
Arithmetic operations on SplFloat objects require explicit type cast to (float) primitive type for expected behavior.

Test script:
---------------
$a = 3;
$b = 1.55;
$c = $a + $b;
echo $c . PHP_EOL; // prints 4.55

$d = new \SplFloat(3.00);
$e = new \SplFloat(1.55);
$f = $d + $e;
echo $f . PHP_EOL; // prints 4 (unexpected)

$g = new \SplFloat(3.00);
$h = new \SplFloat(1.55);
$i = (float)$g + (float)$h;
echo $i . PHP_EOL; // prints 4.55

Expected result:
----------------
4.55
4.55
4.55

Actual result:
--------------
4.55
4
4.55