null textContent value for DocumentFragment

The .textContent attribute of a DocumentFragment—such as the one returned by a <template>’s .content attribute—is null.

import { parseHTML } from "linkedom";

const { document } = parseHTML("");

const template = document.createElement("template");
template.innerHTML = "foo <span>bar</span>";

// in linkedom this is "foo bar", in browsers it’s an empty string
console.log(template.innerText);

const documentFragment = template.content;

// in linkedom this is null, in browsers it’s "foo bar"
console.log(documentFragment.textContent);

Start by locating the DocumentFragment textContent implementation and compare it with the browser behavior shown in the issue’s template.content example. Done means template.content.textContent returns the fragment’s text rather than null, while the demonstrated behavior remains consistent.