Fix issues with some pseudo-elements (#11111)

* Fix issues with some pseudo-elements

We’ve included pseudo elements for backdrop, marker, placeholder, and selection and they were all “jumpable” before we made changes in v3.3.2. Ideally they wouldn’t be because if they ever eventually have any interactivity that could become a problem.

* Update changelog

src/util/pseudoElements.js

@@ -26,17 +26,17 @@
 /** @type {Record<string, PseudoProperty[]>} */
 let elementProperties = {
   '::after': ['terminal', 'jumpable'],
-  '::backdrop': ['terminal'],
+  '::backdrop': ['terminal', 'jumpable'],
   '::before': ['terminal', 'jumpable'],
   '::cue': ['terminal'],
   '::cue-region': ['terminal'],
   '::first-letter': ['terminal', 'jumpable'],
   '::first-line': ['terminal', 'jumpable'],
   '::grammar-error': ['terminal'],
-  '::marker': ['terminal'],
+  '::marker': ['terminal', 'jumpable'],
   '::part': ['terminal', 'actionable'],
-  '::placeholder': ['terminal'],
-  '::selection': ['terminal'],
+  '::placeholder': ['terminal', 'jumpable'],
+  '::selection': ['terminal', 'jumpable'],
   '::slotted': ['terminal'],
   '::spelling-error': ['terminal'],
   '::target-text': ['terminal'],