Bug 1730120, close ContentViewer properly if initialization fails, r=nika

Differential Revision: https://phabricator.services.mozilla.com/D130211

docshell/base/nsDocShell.cpp

@@ -8107,7 +8107,11 @@ nsresult nsDocShell::SetupNewViewer(nsIContentViewer* aNewViewer,
   mContentViewer->SetNavigationTiming(mTiming);
 
   if (NS_FAILED(mContentViewer->Init(widget, bounds, aWindowActor))) {
+    nsCOMPtr<nsIContentViewer> viewer = mContentViewer;
+    viewer->Close(nullptr);
+    viewer->Destroy();
     mContentViewer = nullptr;
+    mCurrentURI = nullptr;
     NS_WARNING("ContentViewer Initialization failed");
     return NS_ERROR_FAILURE;
   }

layout/base/nsDocumentViewer.cpp

@@ -1597,8 +1597,6 @@ static void DetachContainerRecurse(nsIDocShell* aShell) {
 
 NS_IMETHODIMP
 nsDocumentViewer::Destroy() {
-  NS_ASSERTION(mDocument, "No document in Destroy()!");
-
   // Don't let the document get unloaded while we are printing.
   // this could happen if we hit the back button during printing.
   // We also keep the viewer from being cached in session history, since