Tabs without Panels

It would be nice to be able to use tabs without panels. An example use case for this would be to use the tabs to update the location via pushState, with listeners then updating portions of the DOM.

If there isn't a matching mdl-tabs__panel for the clicked tab, then just skip panel logic, set is-active on the clicked tab, and allow the event to fire as normal.

I think an enhancement like this is valuable, as it easily (and optionally) decouples tabs from panels. It allows us to get the UI of tabs, without being tied to hiding/showing divs that must all be present in the DOM (which, as an approach to dynamic content rendering, is a little dated).

I tried to submit a PR, but I can't push a branch to the repo.