add specs to show that tree nodes (proxies) support es6 features such as destructuring objects (NodeObject) and arrays (NodeArray).
add specs to NodeArray to make sure the Array API (slice, map, reduce, filter, find, etc) will behave as expected when called on the tree node proxies.
refactor specs so they use a common theme (todo app for instance) for better consistency.
refactor spec examples so they focus on a single (if possible) aspect of the feature.