Make `HTMLEditor::AutoDeleteRangesHandler::HandleDeleteNonCollapsedRa…

…nges` check if handling range is still editable

In the testcase, editing host is removed when first node removing, but
`HTMLEditor::Destroyed()` still returns `false`.  So, ideally, we should add
a check of editing host validity in `Destroyed()`, but for now, we should make
the method check whether the handling range is still editable after running
each transaction.

Depends on D147723

Differential Revision: https://phabricator.services.mozilla.com/D147724

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1771809
gecko-commit: 8b7e176bb5e0e5abd88dfe5ba66083050468900b
gecko-reviewers: m_kato

editing/crashtests/delete-in-dd-editing-host-after-selectall-with-focus.html

@@ -0,0 +1,12 @@
+<script>
+addEventListener("DOMContentLoaded", () => {
+  document.querySelector("dd[contenteditable]").focus();
+  document.querySelector("dd[contenteditable]").addEventListener("DOMNodeRemoved", () => {
+    document.querySelector("h6").textContent = "";
+  });
+  document.execCommand("selectAll");
+  document.execCommand("delete");
+})
+</script>
+<h6>
+<dd contenteditable>

editing/crashtests/delete-in-dd-editing-host-after-selectall-without-focus.html

@@ -0,0 +1,12 @@
+<script>
+addEventListener("DOMContentLoaded", () => {
+  document.querySelector("dd[contenteditable]").blur();
+  document.querySelector("dd[contenteditable]").addEventListener("DOMNodeRemoved", () => {
+    document.querySelector("h6").textContent = "";
+  });
+  document.execCommand("selectAll");
+  document.execCommand("delete");
+})
+</script>
+<h6>
+<dd contenteditable>