Allow filtering the .htaccess-entry `ExpiresByType text/html` for expert mode

Hi there!

Sorry in advance for this pile of text.

Today I discovered that I can modify the Cache-Control header in expert-mode inside the wp-content/cache/.htaccess file by setting the constant WPSC_CACHE_CONTROL_HEADER in my wp-config.php.

I am doing this now:

define('WPSC_CACHE_CONTROL_HEADER', 'max-age=300, private');

It’s working fine, the Header gets written to the .htaccess file and sent to my browser for cached requests. But then I noticed this line in the same .htaccess:

ExpiresByType text/html A3

“A3” translates to “access plus 3 seconds”, right? If I understand these Headers correctly, now my custom max-age directive can’t be respected due to the 3 seconds ExpiresByType, right?

So basically I would need a constant to also change the ExpiresByType Header. I’m imagining something like this:

define('WPSC_EXPIRES_HTML_HEADER', 'access plus 300 seconds');