idea: merge consecutive paths with same fill?

while looking at some waved flags in noto-emoji, I noticed one where there are dozen (perhaps hundreds, I didn't count -- the svg is probably autotraced which may expain the big numbers) of consecutive paths that have the same fill.

Since in nanoemoji we convert each `` elements to a glyph (to be used as a filled path in COLR PaintGlyph), and the total number of glyphIDs in a font is 65,636, we want to reduce the overall number of layers that each color glyph uses.

What if picosvg makes a single `` out of two or more ``s that have the same fill?
We could use skia-pathops to make a union of the paths..

Start by tracing how picosvg handles consecutive elements and how skia-pathops could union them. Check the resulting layer or glyph counts in a nanoemoji build using the Noto Emoji example. Done means same-fill paths are combined while preserving the SVG rendering and reducing color-glyph layers.

Written by the indexing model from the issue text.