dragging and dropping tabs isn't working

[bgrins]

Open a couple tabs, then try to drag one to the left or right and I see:

tab.jsx:63 Uncaught TypeError: this.props.onDragStart is not a function

Screenshot:

[jsantell]

This was mostly disabled a few weeks ago with some refactor, I wanted to keep it but linting made not using it needlessly frustrating. No idea if worth to keep as we don't know if we'll have tabs, or just remove it.

[victorporof]

I vote removing it