Update styles.php

the fourth parameter of the JHTML::_('select.option',... ) is not anymore valid because it is responsible of a "PHP notice" when we browse template options page in joomla 3.x control panel.

In fact the line :

   return array(JHTML::_('select.option', '', JText::_('No styles are provided for this template'), true));

call the option method of the ""Joomla_PATH"" \libraries\cms\html\select.php file
and pass the "true" parameter to it, but the "true" parameter does not match the method signature which has "now" 5 parameters

The call should be : 
  return array(JHTML::_('select.option', '', JText::_('No styles are provided for this template'), 'value', 'text', true)); 
OR
  return array(JHTML::_('select.option', '', JText::_('No styles are provided for this template'), 'value', 'text', false)); 
Because the last parameter is the "disable" one, and is not used by the "option" method ( according to method comments )
SO .... we can fix that line with : 
   return array(JHTML::_('select.option', '', JText::_('No styles are provided for this template')));
because we use the default parameters value of the "option" method. 

:)