In investigating https://github.com/w3c/css-houdini-drafts/issues/627 , I found that the test case breaks because, for some reason, we are passing a "document" node, instead of the "body" node, into FilteredComputedStylePropertyMap [1], which doesn't have a ComputedStyle. If we change the test case to "div", then everything works because the div has a ComputedStyle.

I suspect we should be passing in the "body" element into FiltedComputedStylePropertyMap, but not really sure how that's done. Assuming that's true, assigning to Blink>Paint because the bug would be in CSSPaintDefinition::Paint.

[1] https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp?q=CSSPaintDefinition::Paint&sq=package:chromium&l=100