Configuration:
- PDF.js version: 2.0.550

Steps to reproduce the problem:
1. Render document in SVG mode `renderMode="svg"`

What is the expected behavior? (add screenshot)
Rendering annotations same way as they rendered on canvas

What went wrong? (add screenshot)
```
Warning: Unimplemented operator beginAnnotations
Warning: Unimplemented operator endAnnotations
```
const descriptor = new Dict(null);
        descriptor.set("Widths", widths);
        dict.set("FontDescriptor", descriptor);
        promises.push(
          partialEvaluator
            .handleSetFont(
              resources,
              [Name.get(name), 1],
               null,
              operatorList,
              task,
              initialState,
               dict,
               {
                fontFamily: missing,
                fontWeight: fontInfo.fontWeight,
                italicAngle: fontInfo.italicAngle,
              }
            )
            .catch(function (reason) {
              warn(`loadXfaFonts: "${reason}".`);
              return null;
            })
        );
      }
    }
    await Promise.all(promises);
    this.xfaFactory.appendFonts(pdfFonts, reallyMissingFonts);
  }
  async serializeXfaData(annotationStorage) {