Disallow vendor prefixes for selectors.
input::-moz-placeholder {}
/** ↑
* These prefixes */
This rule does not blanketly condemn vendor prefixes. Instead, it uses Autoprefixer's up-to-date data (from caniuse.com) to know whether a vendor prefix should cause a violation or not. If you've included a vendor prefixed selector that has a standard alternative, one that Autoprefixer could take care of for you, this rule will complain about it. If, however, you use a non-standard vendor-prefixed selector, one that Autoprefixer would ignore and could not provide, this rule will ignore it.
The following patterns are considered violations:
input::-moz-placeholder {}
:-webkit-full-screen a {}
The following patterns are not considered violations:
input::placeholder {}
:full-screen a {}