code: function (node, pred) {
              node = node.parentNode;
  
              while (node) {
                  if (nodeLength(node) !== 1) { break; }
                  if (pred(node)) { return node; }
                  if (isEditable(node)) { break; }
  
                  node = node.parentNode;
              }
              return null;
          }
docs: find nearest ancestor only single child blood line and predicate hit
  
  @param {Node} node
  @param {Function} pred - predicate function