fetchpriority opportunities

Demos:

• DOM Interactive
• script defer
• fetchpriority
• preload
• Crossorigin images
• preconnect
• preload and fetchpriority
• "Tight mode"
• No render-blocking scripts
• Early preload
• <script> after <img> elements
• defer and fetchpriority="high"
• <script> before <img> elements
• Synchronous JavaScript after CSS
• Images with initial High priority