Fixes regression in TreeItemObserver for determining indexes in sub-observer children.
Improves the delegate and item handling of SC.TreeItemObserver. Includes unit tests.
Adds some documentation to TreeItemObserver explaining what will and won't get observed in tree-data-type terms.
Fixes a regression where tree item observers’ delegates were forced to specify treeItemChildrenKey and treeItemIsExpandedKey. If the delegate doesn’t provide these properties, the defaults are used.