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;
   }