3.6.8 breaks compatibility with WpEmerge blade templates

[andrewostrin]

Hello!

We're using WpEmerge with WpEmerge blade package for blade templates support.
https://github.com/htmlburger/wpemerge-blade

Output buffer call in Block_Container class disrupts blade buffering order and @yield / @section directives stop working properly, whenever a Carbon Fields block is included in content.

Carbon_Fields\Container\Block_Container::452

$toReturn = ob_get_contents();
ob_clean();

Replacing ob_clean() with ob_end_clean() seems to solve the issue with no adverse effects in WP Admin / frontend.