Suggestion: Date.js - toUtc - return this

I would like to suggest that in the Date.js file, the prototype method 
called toUtc, add the line 'return this;' so that it can be chained.  
For example:

var zt = (new Date()).toUtc().format(Date.ISOFORMAT);

I noticed that toLocalTime would also benefit from the same enhancement.

Thanks,
Kris