Remove unused PlatformAtlas::clear method (#4116)

Release Notes:

- N/A

crates/gpui/src/platform.rs

@@ -282,8 +282,6 @@ pub(crate) trait PlatformAtlas: Send + Sync {
         key: &AtlasKey,
         build: &mut dyn FnMut() -> Result<(Size<DevicePixels>, Cow<'a, [u8]>)>,
     ) -> Result<AtlasTile>;
-
-    fn clear(&self);
 }
 
 #[derive(Clone, Debug, PartialEq, Eq)]

crates/gpui/src/platform/mac/metal_atlas.rs

@@ -74,20 +74,6 @@ impl PlatformAtlas for MetalAtlas {
             Ok(tile)
         }
     }
-
-    fn clear(&self) {
-        let mut lock = self.0.lock();
-        lock.tiles_by_key.clear();
-        for texture in &mut lock.monochrome_textures {
-            texture.clear();
-        }
-        for texture in &mut lock.polychrome_textures {
-            texture.clear();
-        }
-        for texture in &mut lock.path_textures {
-            texture.clear();
-        }
-    }
 }
 
 impl MetalAtlasState {

crates/gpui/src/platform/test/window.rs

@@ -325,10 +325,4 @@ impl PlatformAtlas for TestAtlas {
 
         Ok(state.tiles[key].clone())
     }
-
-    fn clear(&self) {
-        let mut state = self.0.lock();
-        state.tiles = HashMap::default();
-        state.next_id = 0;
-    }
 }