[1] Reinstate active flag for iterators (ayg著, ) <https://github.com/whatwg/dom/commit/6a796cc7676263c30550abfd7cc248300d006b2d>
[2] Also unset the active flag when an exception is thrown (annevk著, ) <https://github.com/whatwg/dom/commit/48c4b4aa0d1b4044b7be62d3a75aaab94058161f>
[3] Remove traversal active flag https://www.w3.org/Bugs/Public/show_bug.… (annevk著, ) <https://github.com/whatwg/dom/commit/ccf51e85f205efd8a4497322f35fc39226e6616c>
[4] 25412 – Allow some recursion in NodeIterator/TreeWalker () <https://www.w3.org/Bugs/Public/show_bug.cgi?id=25412>
[5] Reinstate active flag for iterators by ayg · Pull Request #359 · whatwg/dom () <https://github.com/whatwg/dom/pull/359>
[6] "Unset the active flag. " · Issue #494 · whatwg/dom () <https://github.com/whatwg/dom/issues/494>
[7] Also unset the active flag when an exception is thrown by annevk · Pull Request #498 · whatwg/dom () <https://github.com/whatwg/dom/pull/498>