970ea4c511
In order to land https://github.com/flutter/engine/pull/52303 , we need to finally fix the advanced blend draw vertices combo. Right now a ColorFilter is used for advanced blends which doesn't work if there are overlapping vertices. See also: https://github.com/flutter/flutter/issues/145707 The issue was fixed for drawVertices/drawAtlas pipeline blends using the porterduff shader. This extends this to advanced blends, but since drawVertices/atlas with an advanced blend is uncommon and because we don't 15 new shader variants, just add one special uber shader. Part of https://github.com/flutter/flutter/issues/131345