Fix linting error

Author: mzschwartz5

packages/engine/Source/Core/VectorProvider.js

@@ -249,7 +249,7 @@ class VectorProvider {
     const result = {
       show: true,
       minimumTileScreenPixels: this.minimumTileScreenPixels,
-      rectangle: Rectangle.clone(tileRectangle)
+      rectangle: Rectangle.clone(tileRectangle),
     };
 
     for (const collection of this._collections) {