Replace width and height with Widget::size

examples/loading_spinners/src/circular.rs

@@ -244,12 +244,11 @@ where
         tree::State::new(State::default())
     }
 
-    fn width(&self) -> Length {
-        Length::Fixed(self.size)
-    }
-
-    fn height(&self) -> Length {
-        Length::Fixed(self.size)
+    fn size(&self) -> Size<Length> {
+        Size {
+            width: Length::Fixed(self.size),
+            height: Length::Fixed(self.size),
+        }
     }
 
     fn layout(

examples/loading_spinners/src/linear.rs

@@ -165,12 +165,11 @@ where
         tree::State::new(State::default())
     }
 
-    fn width(&self) -> Length {
-        self.width
-    }
-
-    fn height(&self) -> Length {
-        self.height
+    fn size(&self) -> Size<Length> {
+        Size {
+            width: self.width,
+            height: self.height,
+        }
     }
 
     fn layout(