Bug 1872863 - Part 1. Ignore error of GetInlineSpellCheckek. r=masayuki

GeckoView disables spell checker. When disabling it and contenteditable
attribute is changed, we may not initialize editor.

So we should ignore an error of spell check.

Differential Revision: https://phabricator.services.mozilla.com/D202408

dom/base/Document.cpp

@@ -6319,9 +6319,11 @@ void Document::DeferredContentEditableCountChange(Element* aElement) {
     if (aElement) {
       if (RefPtr<HTMLEditor> htmlEditor = GetHTMLEditor()) {
         nsCOMPtr<nsIInlineSpellChecker> spellChecker;
-        rv = htmlEditor->GetInlineSpellChecker(false,
-                                               getter_AddRefs(spellChecker));
-        NS_ENSURE_SUCCESS_VOID(rv);
+        DebugOnly<nsresult> rvIgnored = htmlEditor->GetInlineSpellChecker(
+            false, getter_AddRefs(spellChecker));
+        NS_WARNING_ASSERTION(
+            NS_SUCCEEDED(rvIgnored),
+            "EditorBase::GetInlineSpellChecker() failed, but ignored");
 
         if (spellChecker &&
             aElement->InclusiveDescendantMayNeedSpellchecking(htmlEditor)) {