Fix canvas::Frame issuing a new layer for Mesh2D in with_clip

Text will still be rendered in its own layer, until we fix the composition bottleneck in `glyph-brush`.

graphics/src/widget/canvas/geometry.rs

@@ -22,9 +22,3 @@ impl Geometry {
         self.0
     }
 }
-
-impl From<Geometry> for Primitive {
-    fn from(geometry: Geometry) -> Primitive {
-        geometry.0
-    }
-}