Symbol Stainer: stained type keeps no link to a global swatch

The Symbol Stainer mixed the color of type characters painted with a
global swatch but kept the swatch name and tint, so the characters'
paint named a swatch whose color it no longer had, and a later edit of
the swatch could put the unstained color back. Their fill and stroke now
become plain colors, as a path's paint does.

crates/brush/src/colorize.rs

@@ -119,7 +119,7 @@ pub fn tint_node(n: &mut Node, color: &Color, amount: f32) {
         for r in &mut t.runs {
             for p in [&mut r.style.fill, &mut r.style.stroke] {
                 if let Paint::Solid { color: c, .. } = p {
-                    *c = c.lerp(color, amount);
+                    *p = Paint::solid(c.lerp(color, amount));
                 }
             }
         }

crates/brush/src/tests.rs

@@ -363,6 +363,12 @@ fn stain_mixes_type_strokes_too() {
     let mut art = type_art(red.clone(), red);
     tint_node(&mut art, &blue, 1.0);
     assert_eq!(run_paints(&[art]), [(Paint::solid(blue), Paint::solid(blue))]);
+    // Characters painted with a global swatch lose the link, as a path's paint does: the mixed color
+    // is not the swatch's color.
+    let linked = Paint::Solid { color: Color::rgb(1.0, 0.0, 0.0), swatch: Some("Red".into()), tint: 0.5 };
+    let mut art = type_art(linked.clone(), linked);
+    tint_node(&mut art, &blue, 1.0);
+    assert_eq!(run_paints(&[art]), [(Paint::solid(blue), Paint::solid(blue))]);
 }
 
 #[test]