Font fallback has a bug. When we create a new CkTextStyle with no font fallback, we default it to Roboto (https://github.com/flutter/engine/blob/73c9904f3ecf4000663d74b43518040e11f73d2a/lib/web_ui/lib/src/engine/canvaskit/text.dart#L284). This is incorrect as we should first fallback to a parent style's font or fallback.