function floorf( x ) {
	return addon( x );
}
Rounds a single-precision floating-point number toward negative infinity.

@private
@param {number} x - input value
@returns {number} rounded value

@example
var v = floorf( -4.2 );
// returns -5.0

@example
var v = floorf( 9.99999 );
// returns 9.0

@example
var v = floorf( 0.0 );
// returns 0.0

@example
var v = floorf( NaN );
// returns NaN