LooseMock of goog.dom.AbstractRange. Useful because the mock framework cannot
simply create a mock out of an abstract class, and cannot create a mock out
of classes that implements __iterator__ because it relies on the default
behavior of iterating through all of an object's properties.
Concrete subclass of goog.dom.AbstractRange that simply sets the abstract
method __iterator__ to undefined so that javascript defaults to iterating
through all of the object's properties.