BUG: Load data with many polydata's

Improvements to the WebWorkerPool in itk.js.

Closes #367

Author: thewtex

js/package-lock.json

@@ -62,8 +62,8 @@
     "autoprefixer": "^9.7.6",
     "copy-webpack-plugin": "^5.1.1",
     "css-element-queries": "^1.2.3",
-    "itk": "^13.1.1",
-    "itk-vtk-viewer": "^10.7.3",
+    "itk": "^13.1.3",
+    "itk-vtk-viewer": "^10.7.4",
     "jupyter-dataserializers": "^2.2.0",
     "mobx": "^5.15.4",
     "regenerator-runtime": "^0.13.5",