function isnanf( x ) {
	return Boolean( addon( x ) );
}
Tests if a single-precision floating-point numeric value is `NaN`.

@private
@param {number} x - value to test
@returns {boolean} boolean indicating whether the value is `NaN`

@example
var bool = isnanf( NaN );
// returns true

@example
var bool = isnanf( 7.0 );
// returns false