message: FilterManager shaderCache reset as object
  The shaderCache is initially created as an object. When the Filter Manager gets destroyed, it should be reset to an empty object, not an array.
diff: @@ -484,7 +484,7 @@ export default class FilterManager extends WebGLManager
  */
  destroy()
  {
  - this.shaderCache = [];
  + this.shaderCache = {};
  this.emptyPool();
  }
  