Drip memory usage to increases more quickly than in IE,
making it difficult to monitor memory leaks. This is
because Drip maintains a reference to all watched
elements and does not free them until the "Check Leaks"
button is clicked.
We should implement some kind of cleanup pass that
releases these references for past pages. We want to
avoid releasing these prematurely so that we don't fail
to report leaked items. Can we perhaps free these if no
other references exist to that document object?