We currently do not pixel snap overflow clip paint property nodes:
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp?q=paintpropertytreeb&sq=package:chromium&l=838

This change was made in:
Don't pixel-snap overflow clips in clip paint property nodes.
https://chromium.googlesource.com/chromium/src/+/19b6d116165378bc06ae204d74b5b1da58caa9ab

In my patch to implement composed scrolling in SPV2, using un-snapped composited clip bounds causes the scrolling layer to spill out over the contents in compositing/overflow/fractional-sized-scrolling-layer.html:
https://chromium-review.googlesource.com/c/609317


Some options:
1) We could pixel snap when converting the blink clip paint property node to the cc paint property node.
2) During property tree building we will likely know whether a scroll node will be composited. We could only snap in these cases.


I don't really like any of these options. Do folks have opinions about how to handle this?