This page uses an unaccelerated CSS animation (of width, with height set to auto) to grow "float: right" (class "zm right zoom") boxes containing images on hover.
If you scroll to "SAPPHIRE" and hover the image on the right then at the end of the animation the text overlaps the image. With simple line layout disabled the text does not overlap the image.
Created attachment 221177 [details]
Screenshot of bad overlapping layout
I see this with a build I made using r161903 from yesterday on an elderly macbook air.
I thought this might have been fixed after Zalan's change r162340, but it still persists. Layout is fine with SimpleLineLayout disabled (I just change canUse() to always return false), so I'm pretty sure this is a SimpleLineLayout bug.
Created attachment 221718 [details]
reduced test case
This is definitely a layout issue and not paint coordinates snapping (what my patch addressed)
SimpeLineLayout::canUseFor had code to disable the path for constrained float cases like this. I suspect the cached canUseFor is just not cleared after dynamic style change here. Or the existing test is just insufficient.
Created attachment 231258 [details]