[Editor] Support svg images in the stamp annotation

createImageBitmap doesn't work with svg files (see bug 1841972), so we need to workaround
this in using an Image.
When printing/saving we must rasterize the image, hence we get the biggest bitmap as image
reference to avoid duplications or poor quality on rendering.

test/integration/test_utils.js

@@ -154,3 +154,25 @@ function getEditors(page, kind) {
   }, kind);
 }
 exports.getEditors = getEditors;
+
+function getEditorDimensions(page, id) {
+  return page.evaluate(n => {
+    const element = document.getElementById(`pdfjs_internal_editor_${n}`);
+    const { style } = element;
+    return { width: style.width, height: style.height };
+  }, id);
+}
+exports.getEditorDimensions = getEditorDimensions;
+
+function serializeBitmapDimensions(page) {
+  return page.evaluate(() => {
+    const { map } =
+      window.PDFViewerApplication.pdfDocument.annotationStorage.serializable;
+    return map
+      ? Array.from(map.values(), x => {
+          return { width: x.bitmap.width, height: x.bitmap.height };
+        })
+      : [];
+  });
+}
+exports.serializeBitmapDimensions = serializeBitmapDimensions;