Find what javascript changes the DOM?
Solution 1:
In Chrome dev tools, you have the option of breaking execution when the DOM changes. 
Also a screenshot to illustrate Wolfram's answer (+1)
Solution 2:
A minor addition to Jayraj's answer: Breakpoints on DOM Mutation Events. Right click on any element and you can select Break on Subtree Modifications and Break on Attributes Modifications and Break on Node Removal.
This is also possible using Firebug: right click an element and you have some options to monitor it for changes.