Appears to be working in Firefox but at least Chrome & Safari are broken. Should be a really recent regression so very few possible changes to blame...

Easiest repo: the todo list on our homepage.

if (typeof obj === 'object') {
    if (Array.isArray(obj)) {
      return '[' + obj.map(friendlyStringify).join(', ') + ']';
    } else {
      var pairs = [];
      for (var key in obj) {
        if (Object.prototype.hasOwnProperty.call(obj, key)) {
          var keyEscaped = /^[a-z$_][\w$_]*$/i.test(key) ?
            key :
            JSON.stringify(key);
          pairs.push(keyEscaped + ': ' + friendlyStringify(obj[key]));
        }
      }
      return '{' + pairs.join(', ') + '}';
    }
  } else if (typeof obj === 'string') {
    return JSON.stringify(obj);
  } else if (typeof obj === 'function') {
    return '[function object]';
  }
  
  
  return String(obj);
}
var styleMutationWarning = {};
function checkAndWarnForMutatedStyle(style1, style2, component) {