Consider the chart under "Mobile: Vanilla" heading. It seems to indicate that the total rendering time _drops_ with the number of pictures. That is _almost_ physically impossible. But it is super easy to get that kind of result in benchmarks, e.g. by not properly clearing caches between runs.
Here's a possible explanation (but who knows):
At a certain page height, WebKit/Blink may change rendering behavior. It doesn't need to render elements that are far away from the viewport.
So if the benchmark produces weird results, and is published without source code, so that the results cannot be reproduced, why would anyone trust it?
Even the author suspects the V8 optimized away the vanilla code... and if that is what happened, then apples are being compared to oranges and the whole conclusion is bogus. Which was kind of my point.