function isPositiveZero( x ) {
	return Boolean( addon( x ) );
}
Tests if a double-precision floating-point numeric value is positive zero.

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

@example
var bool = isPositiveZero( 0.0 );
// returns true

@example
var bool = isPositiveZero( -0.0 );
// returns false