Add warning for ambiguous usage of slot-scope and v-for on the same element #6817
Description
Version
2.5.2
Reproduction link
https://jsfiddle.net/xrecft4f/
Steps to reproduce
parent1 is not rendering anything, while parent2 is rendering correctly.
What is expected?
v-for should work if the slot-scope is given on the element.
What is actually happening?
As visible in the fiddle, parent1 is not rendering anything. Right now it only works if it's wrapped inside a template tag.