Use mangle_url() function on 'content_url' and 'plugins_url' filters

[r-a-y]

Proper fix for #33.

[splaquet]

out of curiosity... when the mangle_url function is working correctly, does it re-map the alias/mapped domain for all of the parent domain references?

as an example:
if I'm using domain.com, and I map/alias domainabc.com, the .css/.js/etc are still referencing the domain.com when viewing domainabc.com. and, as expected, this leads to CORS issues.

i'm not exactly sure how to fix that issue via CORS policy update in .htaccess. we're using well over a dozen different domains within our multisite environment.

[r-a-y]

When you are on the alias site, it switches the subdomain asset URLs to the alias URL.

For example, subdomain.example.com/wp-content/plugins/some-plugin/js.js to alias.com/wp-content/plugins/some-plugin/js.js.

This PR helps to fix these assets if a plugin utilizes plugins_url() or content_url() to set their asset URL.

[tomjn]

@r-a-y I see #33 got closed by the author:

Closing this for being a bad idea. Sorry for keeping this open for so long, I just forgot about it.

Does it make sense to close this? I'm not sure what the benefit of doing this is, it was never clearly outlined

[r-a-y]

Thanks for getting to this, @tomjn .

I see #33 got closed by the author

Ping @carstingaxion .

Does it make sense to close this? I'm not sure what the benefit of doing this is, it was never clearly outlined

I mention the utility of this in the comment above.

Some plugins use content_url() or plugin_url() to generate their asset URLs such as CSS, JS, images, etc. Without this PR, the asset URLs by these plugins would use the subdomain host instead of the alias domain host.