perf(track): reduce webgl memory usage (#1057)

* perf: memory

* fix: add back type

src/tracks/gosling-track/gosling-track.ts

@@ -399,7 +399,8 @@ const factory: PluginTrackFactory<Tile, GoslingTrackOptions> = (HGC, context, op
             this.pBackground.clear();
             this.pBackground.removeChildren();
             this.pBorder.clear();
-            this.pBorder.removeChildren();
+            const children = this.pBorder.removeChildren();
+            children.forEach(c => c.destroy());
             this.displayedLegends = [];
 
             // Because a single tile contains one track or multiple tracks overlaid, we draw marks and embellishments