Function findAncestor

docs/index.js:21137–21148

(parent, tagName)

      return null;
    }
    function findAncestor(parent, tagName) {
      for (; parent; ) {
        switch (parent.tag) {
          case 5:
          case 26:
          case 27:
            if (parent.type === tagName) return parent;
        }
        parent = parent.return;
      }
      return null;
    }
    function validateDOMNesting(childTag, ancestorInfo) {
      ancestorInfo = ancestorInfo || emptyAncestorInfoDev;
      var parentInfo = ancestorInfo.current;