Fixed a crash when Destroy(...) was called without first calling Init(...)

git-svn-id: svn://10.0.0.236/trunk@8302 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/docshell/base/nsWebShell.cpp

@@ -600,7 +600,9 @@ nsWebShell::Destroy()
   nsresult rv = NS_OK;
 
   // Stop any URLs that are currently being loaded...
-  mDocLoader->Stop();
+  if (nsnull != mDocLoader) {
+    mDocLoader->Stop();
+  }
 
   // Cancel any timers that were set for this loader.
   CancelRefreshURLTimers();