message: BlurFilter does not clear the result in case of several filters
diff: @@ -39,7 +39,7 @@ export default class BlurFilter extends Filter
  * @param {PIXI.RenderTarget} input - The input target.
  * @param {PIXI.RenderTarget} output - The output target.
  */
  - apply(filterManager, input, output)
  + apply(filterManager, input, output, clear)
  {
  const xStrength = Math.abs(this.blurXFilter.strength);
  const yStrength = Math.abs(this.blurYFilter.strength);
  @@ -49,17 +49,17 @@ export default class BlurFilter extends Filter
  const renderTarget = filterManager.getFilterTexture();
  this.blurXFilter.apply(filterManager, input, renderTarget, true);
  - this.blurYFilter.apply(filterManager, renderTarget, output, false);
  + this.blurYFilter.apply(filterManager, renderTarget, output, clear);
  filterManager.returnFilterTexture(renderTarget);
  }
  else if (yStrength)
  {
  - this.blurYFilter.apply(filterManager, input, output, false);
  + this.blurYFilter.apply(filterManager, input, output, clear);
  }
  else
  {
  - this.blurXFilter.apply(filterManager, input, output, false);
  + this.blurXFilter.apply(filterManager, input, output, clear);
  }
  }
  