Warn if colon shorthand is used on v-if/v-html/etc.

What problem does this feature solve?

I just spent way too long debugging something really weird until I realized I accidentally wrote :v-if instead of v-if.

A warning when wrongly using shorthands like : on “native” vue attributes could prevent this bad experience easily.

What does the proposed API look like?

:v-if="foo"

–> console.warn("You specified v-bind:/ v-on: or a corresponding shorthand on a Vue attribute like v-if or similar. Usually this does not make sense.)

[posva]

I’ve seen this happen so often when teaching Vue that even though having a prop named vIf is technically valid, I think this warning would help much more people than ever hurt

[oielbanna]

I was going to give it a go but it seems there’s a super old PR for this already