$attrs changes in migration guide

[skirtles-code]

I can't find this documented anywhere in the migration guide:

https://github.com/vuejs/rfcs/blob/master/active-rfcs/0031-attr-fallthrough.md

Some key points:

• $listeners has been removed. The listeners will now be included in $attrs by default. Use emits to stop them being included in $attrs.
• The native modifier has been removed. It is no longer required now that events are included in $attrs.
• Vue 2 components that were listening for events just so they could re-emit them may not need to do that anymore. Specifically, if the event occurs on the same element that receives the $attrs (the root element by default) the event will already be in the $attrs and doesn't need emitting explicitly. Without changes, Vue 2 components using this pattern will emit the same event twice each time it occurs.
• class and style are now in $attrs and are not separately applied to the root element. They can be removed from $attrs by listing them in the props.
• As a result of the changes to $attrs, the setting inheritAttrs has a much greater impact than it did in Vue 2.