added proptypes for asset

src/components/target-pane/target-pane.jsx

@@ -82,11 +82,9 @@ const TargetPane = ({
             {stage.id && <StageSelector
                 asset={
                     stage.costume &&
-                    // TODO: set correct prop type for this
-                    stage.costume.asset // eslint-disable-line react/prop-types
+                    stage.costume.asset
                 }
-                // TODO: set correct prop type for this
-                backdropCount={stage.costumeCount} // eslint-disable-line react/prop-types
+                backdropCount={stage.costumeCount}
                 id={stage.id}
                 selected={stage.id === editingTarget}
                 onSelect={onSelectSprite}
@@ -106,6 +104,8 @@ const TargetPane = ({
 
 const spriteShape = PropTypes.shape({
     costume: PropTypes.shape({
+        // asset is defined in scratch-storage's Asset.js
+        asset: PropTypes.object, // eslint-disable-line react/forbid-prop-types
         url: PropTypes.string,
         name: PropTypes.string.isRequired,
         // The following are optional because costumes uploaded from disk
@@ -114,6 +114,7 @@ const spriteShape = PropTypes.shape({
         rotationCenterX: PropTypes.number,
         rotationCenterY: PropTypes.number
     }),
+    costumeCount: PropTypes.number,
     direction: PropTypes.number,
     id: PropTypes.string,
     name: PropTypes.string,