Fix Y-flipped lighting in accelerated SVG reference filters in CSS. Since the compositor draws all quads as origin-TopLeft, but Skia expects all render targets (and external textures) to be origin-BottomLeft, accelerated filters were being Y-flipped twice. Since all of the CSS filters have symmetrical parameters, no-one noticed. However, SVG filters (e.g., feSpecularLighting) have parameters which are not symmetrical in Y, so the lighting appeared upside-down.
Now that we have support in Skia for origin-TopLeft render targets, mark both the textures and render targets as origin-TopLeft, to reflect the compositor's convention.
BUG: See webkit.org/b/104289