Add recipe showing common HTML / style assertions

[bahmutov]

• find all elements with inline styles (good to make sure there are none for more secure pages). use *[style] selector.
• images that failed to load (use naturalWidth property)
• checking computed style property like is the element's background red, or color is black
• element is overlapping with other elements
• maybe any images that took longer than N ms to load (using performance metric)

[gabbersepp]

Can you give me a hint on how to measure image load time? As far as I know I can not spy on requests that are no xhr requests. I already found out how I can measure page load time B using window.performance

// Edit: OK, found out how this is working. I took a deeper look at window.performance