code: private static boolean _isAlreadyCompressed (final String sFilename)
    {
      for (final String sExt : EXTENSIONS_JS_COMPRESSED)
        if (sFilename.endsWith (sExt))
          return true;
      return false;
    }
docs: Check if the passed file is already compressed. The check is only done
  using the file extension of the file name.
  
  @param sFilename
  The filename to be checked.
  @return <code>true</code> if the file is already compressed.