Remove comments inside the loop template to enable :empty selector on empty items

[wasil-cz]

please remove unnecessary content from the loop template, so the loop wrappers with no content can be treated by css selector :empty

steps to reproduce:

• have a post widget with a custom post grid of e.g. 10 loop items
• set the post count to e.g. 5 in the query settings, so not all positions in the grid get populated
• inspect the rendered result to see that also the empty positions have their wrappers rendered.
• try to hide those empty loop items with :empty { display: none; } result:
• empty items still visible as they contain <!-- comments -->and empty spaces.

expected result:

• empty items hidden

suggested solution:

• remove comments from the loop template
• remove empty spaces

thanks!