* make SimpleText::add_run accept glyph_transform and style parameters so it doesn't unconditionally do oblique strokes
* replace fill/stroke methods on DrawGlyphs with a single draw method that accepts either fill or stroke styles
* update peniko rev to access the new style types used above
* for now, change glyph cache to only cache non-zero fills. Prior to this, style was ignored in the key which could lead to incorrect rendering.