enable garbage collection for 3D (again)

src/client.js

@@ -102,6 +102,7 @@ document.addEventListener('DOMContentLoaded', () => {
               ProtocolClient.deRegisterChunk([xc, yc]);
             }
             chunks.delete(key);
+            value.destructor();
           }
         }
       });

src/ui/ChunkLoader3D.js

@@ -58,6 +58,10 @@ class ChunkLoader {
     return 0;
   }
 
+  getAllChunks() {
+    return this.chunks;
+  }
+
   getVoxelUpdate(
     xc: number,
     zc: number,

src/ui/ChunkRGB.js

@@ -8,14 +8,13 @@ import { TILE_SIZE } from '../core/constants';
 
 class ChunkRGB {
   cell: Array;
-  key: string;
   image: HTMLCanvasElement;
   ready: boolean;
   timestamp: number;
   palette: Palette;
   isBasechunk: boolean;
 
-  constructor(palette: Palette, key, zoom = 0, cx = 0, cy = 0) {
+  constructor(palette: Palette, zoom = 0, cx = 0, cy = 0) {
     // isBasechunk gets set to true by RECEIVE_BIG_CHUNK
     // if true => chunk got requested from api/chunk and
     //            receives websocket pixel updates
@@ -25,12 +24,16 @@ class ChunkRGB {
     this.image = document.createElement('canvas');
     this.image.width = TILE_SIZE;
     this.image.height = TILE_SIZE;
-    this.key = key;
     this.cell = [zoom, cx, cy];
     this.ready = false;
     this.timestamp = Date.now();
   }
 
+  // eslint-disable-next-line class-methods-use-this
+  destructor() {
+    return null;
+  }
+
   fromBuffer(chunkBuffer: Uint8Array) {
     const imageData = new ImageData(TILE_SIZE, TILE_SIZE);
     const imageView = new Uint32Array(imageData.data.buffer);

src/ui/Renderer3D.js

@@ -262,7 +262,7 @@ class Renderer {
   // TODO use GC to dispose unused chunks
   // eslint-disable-next-line class-methods-use-this
   getAllChunks() {
-    return null;
+    return this.chunkLoader.getAllChunks();
   }
 
   renderPixel(