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
```
expect(appearance).toEqual(
        "/Tx BMC q BT /Goth 5 Tf 1 0 0 1 2 2 Tm" +
          " (\x30\x53) Tj 8.00 0 Td (\x30\x93) Tj 8.00 0 Td (\x30\x6b) Tj" +
          " 8.00 0 Td (\x30\x61) Tj 8.00 0 Td (\x30\x6f) Tj" +
          " 8.00 0 Td (\x4e\x16) Tj 8.00 0 Td (\x75\x4c) Tj" +
          " 8.00 0 Td (\x30\x6e) Tj ET Q EMC"
      
    }
    it("should save text", async function () {
      const textWidgetRef = Ref.get(123, 0
      const xref = new XRefMock([
        { ref: textWidgetRef, data: textWidgetDict },
        helvRefObj,
      ]
      partialEvaluator.xref = xref;
      const task = new WorkerTask("test save"
      const annotation = await AnnotationFactory.create(
        xref,
        textWidgetRef,
        pdfManagerMock,
        idFactoryMock
      
      const annotationStorage = new Map(
      annotationStorage.set(annotation.data.id, { value: "hello world" }
      const data = await annotation.save(
        partialEvaluator,
        task,
        annotationStorage