Slots Unification

Here is a quick summary of what has changed:

• now exposes slots as functions

When using the render function, i.e., , 2.x used to define the slot data property on the content nodes.

In 3.x, render functions will have a option where they can be defined instead.

A majority of the change has already been shipped in 2.6. As a result, the migration can happen in one step:

1. Replace all occurrences with this.$slots in 3.x.