Function shape_canonical_strings 

pub fn shape_canonical_strings(fs: &mut FontSystem) -> usize

Shape every entry of CANONICAL_STRINGS through the supplied FontSystem. Populates the internal shape / fallback caches so the first real draw against the same FontSystem short-circuits at those cache lookups.

Returns the number of glyph runs emitted across every buffer — tests assert > 0 to verify shaping emitted glyph runs rather than silently no-op’ing on a stripped fallback font set.