ation-xml-custom',
];
const invalidCustomElementNames = [
  '',
  'annotation-xml',
  'color-profile',
  'font-face',
  'font-face-src',
  'font-face-uri',
  'font-face-format',
  'font-face-name',
  'missing-glyph',
];

const testCodePoints = [0x1F171, 0x1F196, 0x10000];
for (let i = 0; i < 0x80; i++) {
  testCodePoints.push(i);
}

const elementLocalNameRegex = /^(?:[A-Za-z][^\0\t\n\f\r\u0020/>]*|[:_\u0080-\u{10FFFF}][A-Za-z0-9-.:_\u0080-\u{10FFFF}]*)$/u;

function isValidCustomElementName(str) {
  if (!st