Replace width and height with Widget::size

widget/src/lazy/component.rs

@@ -244,12 +244,8 @@ where
         self.rebuild_element_if_necessary();
     }
 
-    fn width(&self) -> Length {
-        self.with_element(|element| element.as_widget().width())
-    }
-
-    fn height(&self) -> Length {
-        self.with_element(|element| element.as_widget().height())
+    fn size(&self) -> Size<Length> {
+        self.with_element(|element| element.as_widget().size())
     }
 
     fn size_hint(&self) -> Size<Length> {

widget/src/lazy/responsive.rs

@@ -135,12 +135,11 @@ where
         })
     }
 
-    fn width(&self) -> Length {
-        Length::Fill
-    }
-
-    fn height(&self) -> Length {
-        Length::Fill
+    fn size(&self) -> Size<Length> {
+        Size {
+            width: Length::Fill,
+            height: Length::Fill,
+        }
     }
 
     fn layout(