Type: the harakat Tsume test also compares advances

With Noto Sans Arabic the fatha's ink reaches past the first letter's
left edge, so that letter's Tsume only narrows its advance and moves no
glyph. The test compared glyph positions alone and found no change.
It now compares each glyph's position and advance.

crates/text/src/tests/harakat.rs

@@ -403,13 +403,15 @@ fn check_optical_tsume(db: &FontDb, family: &str) {
         }
         t
     };
-    let xs = |t: &TextObject| layout(db, t).glyphs.iter().map(|g| g.xf.as_coeffs()[4]).collect::<Vec<_>>();
+    // Each glyph's place and advance: where a mark's ink leaves no blank space on the left, the
+    // Tsume of the line's first cluster only narrows its advance and moves no glyph.
+    let xs = |t: &TextObject| layout(db, t).glyphs.iter().flat_map(|g| [g.xf.as_coeffs()[4], g.advance]).collect::<Vec<_>>();
     assert!(xs(&set(true, None)).iter().zip(xs(&set(false, None))).any(|(a, b)| (a - b).abs() > 1e-6), "{family}: Optical moves the pair");
     // Each letter in turn: the first one's cluster ends the pair, the second one's starts it.
     for letter in [0, 4] {
         let moved = |optical: bool| xs(&set(optical, Some(letter))).iter().zip(xs(&set(optical, None))).map(|(a, b)| a - b).collect::<Vec<_>>();
         let (without, with_optical) = (moved(false), moved(true));
-        assert!(without.iter().any(|m| m.abs() > 1e-3), "{family} {letter}: Tsume moves the glyphs: {without:?}");
+        assert!(without.iter().any(|m| m.abs() > 1e-3), "{family} {letter}: Tsume moves or narrows the glyphs: {without:?}");
         assert!(
             without.len() == with_optical.len() && without.iter().zip(&with_optical).all(|(a, b)| (a - b).abs() < 1e-6),
             "{family} {letter}: {without:?} {with_optical:?}"