Bug 749981 will remove getUserData and setUserData. The two instances where we use these two functions in browser/devtools/debugger/debugger-controller.js and browser/devtools/debugger/debugger-view.js should be replaced by WeakMaps, as suggested in bug 723062 comment 36.

I'm not sure if we actually need WeakMaps here. A trivial temporary workaround would just be attaching the script data as a property to the object (not sure why we used setUserData in the first place, reading through the code now I don't see a convincing reason, maybe I'm wrong), with a glorified ulterior fix in bug 707302.