Fix a memory leak.

Fix a memory leak.

The toBoundingBoxes function creates a ModelList of models that are already
in another list.  That list laters falls out of scope, but since the models
hold a reference to every list that contains them, the list is kept alive.
This branch introduces code that removes the models from the temporary list
after it has served its purpose.

https://code.launchpad.net/~benji/juju-gui/plug-memory-leak-3/+merge/164765

(do not edit description out of merge proposal)

[benji, 2013-05-20 16:20:56]

Please take a look.

[matthew.scott, 2013-05-20 16:23:46]

LGTM!  Thanks for finding and fixing this.

[jeff.pihach, 2013-05-20 17:27:08]

LGTM Thanks for this!

[benji, 2013-05-20 18:45:08]

*** Submitted:

Fix a memory leak.

The toBoundingBoxes function creates a ModelList of models that are already
in another list.  That list laters falls out of scope, but since the models
hold a reference to every list that contains them, the list is kept alive.
This branch introduces code that removes the models from the temporary list
after it has served its purpose.

R=matthew.scott, jeff.pihach
CC=
https://codereview.appspot.com/9590043