[jdom-interest] addAll(Collection c) throws out of bounds exception

[Jason Hunter]

Jochen Strunk wrote:
> 
> List children = element.getChildren();
> children.addAll(newChildren);
> 
> throws an IndexOutOfBoundsException.
> 
> This only happens when having mixed content because then
> backingList.indexOf(getLast()) in addAll(Collection c)
> might exceed the size of partial list.

Care to submit a patch?  My focus is off PartialList since we're
entirely reimplementing it, but if you have a patch I'll integrate it.

-jh-