This issue is part of #1333730: [Meta] PHP DOM (libxml2) misinterprets HTML5.
The Drupal\system\Tests\Theme\FunctionsTest needs to be upgraded to HTML5.
Blocked on #2667340: Usage of field_prefix and container-inline creates invalid markup. which was fixed in #3072752: Invalid markup in ImageItem (causes test failures with symfony/dom-crawler:4.3+).
Beta phase evaluation
| Issue priority | Major because the testing system needs HTML5 support to test HTML5 code. |
|---|---|
| Prioritized changes | The main goal of this issue is a bugfix to for HTML5 support, which is part of the Drupal 8 product. |
Commit credits
Please give commit credits to all who have worked on the parent issue (#1333730: [Meta] PHP DOM (libxml2) misinterprets HTML5).