[css-flexbox-1] `-webkit-` Legacy properties already defined in compat

The ED of CSS Flexbox Level 1 has an appendix that defines [`-webkit-` legacy properties](https://drafts.csswg.org/css-flexbox-1/#webkit-aliases). These legacy properties are already defined in the [Compatibility](https://compat.spec.whatwg.org/#css-simple-aliases) spec, creating duplicates. Is that intended? (For example, is the plan to move the definitions from compat to css-flexbox?)