Adjust warmConnections if using nocookie attribute, add profile image domain

[mrwweb]

From what I can see, it seems that the warmConnections() function will preconnect to all of these domains regardless of the nocookie attribute:

• https://i.ytimg.com/
• https://s.ytimg.com
• https://www.youtube.com
• https://www.google.com
• https://googleads.g.doubleclick.net
• https://static.doubleclick.net

Looking at a request to youtube-nocookie.com, I think the only connections that should preconnect should be:

• https://i.ytimg.com/
• https://s.ytimg.com
• https://www.youtube-nocookie.com

Looking at an embed request, I'm also seeing that YouTube profile icons are loaded from https://yt3.ggpht.com, so that would be a good one to add to both preconnect lists.

I'm willing to take a stab at a PR if you agree and think this makes sense.

[XhmikosR]

@mrwweb I totally agree with your OP. Could you please make a PR?

@justinribeiro: @mrwweb is right in his observations :)

[justinribeiro]

I concur; I'll either take a PR for this or I'll put it on the list this week.