[css-pseudo] [css-content] add new type of content that clones the text within the node

I suggest a new keyword to be added to the content property which duplicates the textContent DOM property, instead of developers having to define the same text twice, when a pseudo-element is needed to have the same text content as its node.

I suggest to name it text. I was considering contents but it might imply it will use innerHTML as content, instead of the textContent property.

<p class='foo'>Hello world</p>

.foo {
  position: relative;
}

.foo {
  content: text; /* same as manually typing "Hello world" */
  position: absolute;
  z-index: -1;
}

Such use-uses are very common, to achieve visual effects and what not, for example:

https://jsbin.com/livamiwadu/edit?html,css,output

where the text has an outer glow using a filter property, but the text itself is still crisp.

Start by reviewing the linked MDN documentation for the CSS content property and the issue's examples of pseudo-element text duplication. Determine whether a text keyword matching the node's textContent is appropriate, then document the agreed syntax and behavior in the relevant CSSWG draft.