1. Use the Network Link Conditioner (http://nshipster.com/network-link-conditioner/) to make the network slow 2. Open the reproduction html 3. Click somewhere 4. Wait a little while Actual behavior: Red rectangle gets very narrow for a split second before jumping back to its original size Expected behavior: Red rectangle never changes size Firefox / Chrome display the expected behavior. The link that we load when clicking (https://placehold.it/200x200) returns a 301. Initial guess is that we're firing the onload event upon receiving the 301, rather than the subsequent 200.
This was reported by https://twitter.com/jordan_thomas/status/720270360944357377
Created attachment 276408 [details] Reproduction
<rdar://problem/25731182>
<rdar://problem/25731147>
This must be a regression. Would be great if somebody could pinpoint when.
If this is a regression, it's been in a while. On Chrome I see no flash, on Firefox I see a blue flash, and on Safari I see a flash of the rectangle of a different size. Also, from similar tests I'm pretty sure the 301 is not initiating the onload, but from reading the JavaScript it seems like that's what's going on.
I opened the reproduction html in v6.0.5 (7536.30.1) and see the "bounce" behavior there too. I also tried v5.1.9 (6534.59.8) and did _not_ see the behavior (although it does render the demo a little funky).