Do not evaluate scripts or fire error/load events, if <script> elements are moved between Documents during fetching. Script elements can be still moved between Documents, but they won't be executed.
This is to prevent possible security bug, because there have been several bad XSS-related bugs in Chromium due to the code path for executing <script> elements moved between Documents.
Docs: https://github.com/whatwg/html/issues/2469 https://github.com/whatwg/html/pull/2673 https://github.com/web-platform-tests/wpt/pull/5911 https://www.chromestatus.com/metrics/feature/timeline/popularity/2528