fix onSizeUpdated issue for demo

demo/.eslintrc.js

 module.exports = {
   root: true,
   extends: '@react-native-community',
+  rules: {
+    'prettier/prettier': [
+      {
+        singleQuote: true
+      }
+    ]
+  }
 };

demo/App.js

           console.log(result);
           return true;
         }}
-        onSizeUpdated={heightSize => setHeightSize(heightSize)}
+        onSizeUpdated={setHeightSize}
         source={{ html: heightHtml }}
         customScript={heightScript}
         onMessage={event => {
           console.log(result);
           return true;
         }}
-        onSizeUpdated={widthSize => setWidthSize(widthSize)}
+        onSizeUpdated={setWidthSize}
         source={{ html: widthHtml }}
         customScript={widthScript}
       />