Theme suggestions for blocks in a region which has a dash in the name
Per the Theme suggestion docs you linked to the format for region-specific block templates go like this:


  An example of a region-specific template would be "block--sidebar_first.tpl.php"


It looks like Drupal flips _ and - in theme suggestions so 


  block__header-top


becomes


  block--header_top.tpl.php


(I knew it replaced _ with - but I didn't know it was the other way round too; there may be more to it than that).