Backed out changeset 991cb2487be8 (bug 1375940)

layout/base/PresShell.cpp

@@ -7949,8 +7949,7 @@ PresShell::HandleEventWithTarget(WidgetEvent* aEvent, nsIFrame* aFrame,
   if (aContent) {
     nsIDocument* doc = aContent->GetComposedDoc();
     NS_ASSERTION(doc, "event for content that isn't in a document");
-    // NOTE: We don't require that the document still have a PresShell.
-    // See bug 1375940.
+    NS_ASSERTION(!doc || doc->GetShell() == this, "wrong shell");
   }
 #endif
   NS_ENSURE_STATE(!aContent || aContent->GetComposedDoc() == mDocument);