Attach (recommended) or Link to PDF file here:
https://guichet.public.lu/dam-assets/catalogue-formulaires/tva/tva-option-aic-pers-morales/tva-option-aic-pers-morale-DE.pdf

Configuration:
- Web browser and its version: Firefox Nightly 91.0a1 (2021-06-26) (64-bit)
- Operating system and its version: Windows 10.0.19043.1052
- PDF.js version: N/A

Steps to reproduce the problem:
1. enableXFA in Firefox Nightly
2. Open form

What is the expected behavior? (add screenshot)
Header image is scaled properly
![image](https://user-images.githubusercontent.com/7104454/123525954-905d1f00-d6a2-11eb-840e-be30eee395e1.png)

What went wrong? (add screenshot)
Image is scaled to fit
![image](https://user-images.githubusercontent.com/7104454/123525957-96530000-d6a2-11eb-9991-bf7f37c6f1a5.png)


annotationLayerCanvas = document.createElement("canvas");
                    self.annotationLayerCanvas = annotationLayerCanvas;
                  }
                  annotationLayerCanvas.width = viewport.width;
                  annotationLayerCanvas.height = viewport.height;
                  var annotationLayerContext =
                    annotationLayerCanvas.getContext("2d");
                  annotationLayerContext.clearRect(
                    0,
                    0,
                    annotationLayerCanvas.width,
                    annotationLayerCanvas.height
                  );
                  if (!renderXfa) {
                    
                    
                    initPromise = page
                      .getAnnotations({ intent: "display" })
                      .then(function (annotations) {
                        return rasterizeAnnotationLayer(
                          annotationLayerContext,
                          viewport,
                          annotations,
                          page,
                          IMAGE_RESOURCES_PATH,
                          renderForms
                        );
                      });
                  } else {
                    initPromise = page.getXfa().then(function (xfa) {