Rename <slot> to <placeholder>

[padcom]

While working on webcomponents with Vue.js it occurred to me that it is extremely confusing that in both technologies two very different concepts are called exactly the same.

A <slot> in webcomponents is a place where pre-existing DOM elements will be placed. However, in Vue.js it is actually a place where templates will be rendered in. In effect, in Vue.js, what is currently called a <slot> is actually a placeholder for rendering templates. Furthermore, there is no such thing as named slots in webcomponents. Those should be called scoped placeholders in Vue.js, which is a much more precise description of the idea being implemented.

I know this is probably never going to happen, but I still would like to put it under consideration to make sure those 2 concepts can be clearly distinguished.