Bug 1142841: Convert all nsRefPtr<nsIRunnable> to nsCOMPtr<nsIRunnable>. r=ehsan

This patch was generated by a script.  Here's the source of the script for
future reference:

find . \( -iname "*.cpp" -o -iname "*.h" \) | \
  xargs -n 1 sed -i "s/nsRefPtr<nsIRunnable>/nsCOMPtr<nsIRunnable>/g"

netwerk/cache/nsDiskCacheDeviceSQL.cpp

@@ -757,7 +757,7 @@ nsApplicationCache::Discard()
 
   mValid = false;
 
-  nsRefPtr<nsIRunnable> ev =
+  nsCOMPtr<nsIRunnable> ev =
     new nsOfflineCacheDiscardCache(mDevice, mGroup, mClientID);
   nsresult rv = nsCacheService::DispatchToCacheIOThread(ev);
   return rv;