Fix scrollTop problem in chrome

I'm new here.

I think that there's a problem calling body.scrollTop in Chrome, the position of mouse doesn't get a good mouseY position (chrome says that body.scrollTop is deprecated). 

My solution is adding two lines after line 8227 in function calculateOffset(curEvent, event):

<code>offsetX += document.documentElement.scrollLeft;</code>
<code>offsetY += document.documentElement.scrollTop;</code>

But sure there is a better solutions, i'll be waiting new tips...