Only if you inherit every object in your application from their "goog.Disposable" super class and call object.dispose() whenever you want to get rid of it. This kind of negates the point of garbage collection. If you aren't removing event handlers when you destroy objects then it's your own fault.
The title is misleading. This is a new tool for Closure, and <i>possibly</i> other code if you rewrite your code base to work like Closure.<p>The built in developer tools are already good enough for finding leaks in most cases. I just use heap snapshots to make sure there are no ugly leaks.