Fix underline flickering (#35989)

Closes #35559

Release Notes:

- Fixed underline flickering

crates/gpui/src/scene.rs

@@ -476,7 +476,7 @@ pub(crate) struct Underline {
     pub content_mask: ContentMask<ScaledPixels>,
     pub color: Hsla,
     pub thickness: ScaledPixels,
-    pub wavy: bool,
+    pub wavy: u32,
 }
 
 impl From<Underline> for Primitive {

crates/gpui/src/window.rs

@@ -2814,7 +2814,7 @@ impl Window {
             content_mask: content_mask.scale(scale_factor),
             color: style.color.unwrap_or_default().opacity(element_opacity),
             thickness: style.thickness.scale(scale_factor),
-            wavy: style.wavy,
+            wavy: if style.wavy { 1 } else { 0 },
         });
     }
 
@@ -2845,7 +2845,7 @@ impl Window {
             content_mask: content_mask.scale(scale_factor),
             thickness: style.thickness.scale(scale_factor),
             color: style.color.unwrap_or_default().opacity(opacity),
-            wavy: false,
+            wavy: 0,
         });
     }