First merge

`method-list` (for adding breakpoints) isn't ready yet because `core-selector`  is buggy.
The plan is to put `method-list` and `object-tree` on the right side in separate tabs. But `paper-tabs` was  not being compliant with `vulanize`, so that's not done yet.

Requires `O.o()` to work.

Thank you

<b>Update for #2:</b>
`core-selector` still needs to be rewritten and so `method-list` (for breakpoints) is kind of buggy.
Issue with `paper-tabs` got sorted out, so there are tabs on the right now.

The object tree shows all the *own* properties of a selected non-Polymer element (Polymer elements have properties explored across multiple levels of the prototype chain)
So there is no way someone can see properties in higher prototype objects. A good way to allow that is to show the `__proto__` property and allow the user to expand that.
It was an edge case here, since `__proto__` is not an own property of an element, but a getter defined on `Object.prototype`.