Add existing to tracked

node_modules/@cesium/engine/Source/Scene/TileDiscardPolicy.js

@@ -0,0 +1,34 @@
+import DeveloperError from "../Core/DeveloperError.js";
+
+/**
+ * A policy for discarding tile images according to some criteria.  This type describes an
+ * interface and is not intended to be instantiated directly.
+ *
+ * @alias TileDiscardPolicy
+ * @constructor
+ *
+ * @see DiscardMissingTileImagePolicy
+ * @see NeverTileDiscardPolicy
+ */
+function TileDiscardPolicy(options) {
+  DeveloperError.throwInstantiationError();
+}
+
+/**
+ * Determines if the discard policy is ready to process images.
+ * @function
+ *
+ * @returns {boolean} True if the discard policy is ready to process images; otherwise, false.
+ */
+TileDiscardPolicy.prototype.isReady = DeveloperError.throwInstantiationError;
+
+/**
+ * Given a tile image, decide whether to discard that image.
+ * @function
+ *
+ * @param {HTMLImageElement} image An image to test.
+ * @returns {boolean} True if the image should be discarded; otherwise, false.
+ */
+TileDiscardPolicy.prototype.shouldDiscardImage =
+  DeveloperError.throwInstantiationError;
+export default TileDiscardPolicy;