Bug 1221868 - Correct the document check for appending a document fragment node; r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D101339

dom/base/nsINode.cpp

@@ -2523,7 +2523,7 @@ nsINode* nsINode::ReplaceOrInsertBefore(bool aReplace, nsINode* aNewChild,
     fragChildren->SetCapacity(count);
     for (nsIContent* child = newContent->GetFirstChild(); child;
          child = child->GetNextSibling()) {
-      NS_ASSERTION(child->GetComposedDoc() == nullptr,
+      NS_ASSERTION(child->GetUncomposedDoc() == nullptr,
                    "How did we get a child with a current doc?");
       fragChildren->AppendElement(child);
     }

testing/web-platform/meta/custom-elements/adopted-callback.html.ini

@@ -1,5 +1,4 @@
 [adopted-callback.html]
-  max-asserts: 8
   [Moving the <template>'s content of a custom element from the owner document into an HTML document fetched by XHR must enqueue and invoke adoptedCallback]
     expected: FAIL