Add existing to tracked

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

@@ -0,0 +1,46 @@
+// @ts-check
+
+/**
+ * The horizontal location of an origin relative to an object, e.g., a {@link Billboard}
+ * or {@link Label}.  For example, setting the horizontal origin to <code>LEFT</code>
+ * or <code>RIGHT</code> will display a billboard to the left or right (in screen space)
+ * of the anchor position.
+ * <br /><br />
+ * <div align='center'>
+ * <img src='Images/Billboard.setHorizontalOrigin.png' width='648' height='196' /><br />
+ * </div>
+ *
+ * @enum {number}
+ *
+ * @see Billboard#horizontalOrigin
+ * @see Label#horizontalOrigin
+ */
+const HorizontalOrigin = {
+  /**
+   * The origin is at the horizontal center of the object.
+   *
+   * @type {number}
+   * @constant
+   */
+  CENTER: 0,
+
+  /**
+   * The origin is on the left side of the object.
+   *
+   * @type {number}
+   * @constant
+   */
+  LEFT: 1,
+
+  /**
+   * The origin is on the right side of the object.
+   *
+   * @type {number}
+   * @constant
+   */
+  RIGHT: -1,
+};
+
+Object.freeze(HorizontalOrigin);
+
+export default HorizontalOrigin;