Bug 488046 - Some random crash in [@ nsDocShell::EnsureContentViewer], r=bzbarsky

--HG--
extra : rebase_source : 3ce888953aef4d9e402fb0d23085de8c840ea55d

docshell/base/nsDocShell.cpp

@@ -6199,7 +6199,7 @@ nsDocShell::CreateAboutBlankContentViewer(nsIPrincipal* aPrincipal,
         viewer->SetDOMDocument(domdoc);
 
         SetCurrentURI(blankDoc->GetDocumentURI(), nsnull, PR_TRUE);
-        rv = NS_OK;
+        rv = mIsBeingDestroyed ? NS_ERROR_NOT_AVAILABLE : NS_OK;
       }
     }
   }