Not searching for null value for elementClassName in prototypejs 1.7

[Nabarun]

In prototypejs 1.5 we were verifying for null value which we are not doing in 1.7

Current 1.7 version has the following

hasClassName: function(element, className) {
if (!(element = $(element))) return;
var elementClassName = element.className;
return (elementClassName.length > 0 && (elementClassName == className ||
new RegExp("(^|\s)" + className + "(\s|$)").test(elementClassName)));
},

In 1.5 we were having the following

hasClassName: function(element, className) {
if (!(element = $(element))) return;
var elementClassName = element.className;
if (elementClassName == null || elementClassName.length == 0) return false;
if (elementClassName == className ||
elementClassName.match(new RegExp("(^|\s)" + className + "(\s|$)")))
return true;
return false;
},

Because of this issue one of my existing feature was breaking. I solved the issue by adding
if(typeof elementClassName === "undefined") return false;
to 1.7 version

Let me know if this is intended or can be considered as bug