Function roundtrip

test/walkHtmlTokens.unittest.js:875–901

(html)

		 * @returns {string} reconstructed html
		 */
		const roundtrip = (html) => {
			/** @type {unknown[]} */
			const parts = [];
			walkHtmlTokens(html, 0, {
				openTag: (input, start, end) => {
					parts.push(input.slice(start, end));
					return end;
				},
				closeTag: (input, start, end) => {
					parts.push(input.slice(start, end));
					return end;
				},
				comment: (input, start, end) => {
					parts.push(input.slice(start, end));
					return end;
				},
				doctype: (input, start, end) => {
					parts.push(input.slice(start, end));
					return end;
				},
				text: (input, start, end) => {
					parts.push(input.slice(start, end));
					return end;
				}
			});
			return parts.join("");
		};

		// --- STATE_TAG_OPEN ---
		it("tAG_OPEN: `<?xml ?>` becomes bogus comment", () => {