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
```
constructor(pdfManager, arg) {
    let stream;
    if (isStream(arg)) {
      stream = arg;
    } else if (isArrayBuffer(arg)) {
      stream = new Stream(arg);
    } else {
      throw new Error("PDFDocument: Unknown argument type");
    }
    if (stream.length <= 0) {
      throw new InvalidPDFException(
        "The PDF file is empty, i.e. its size is zero bytes."
      );
    }
    this.pdfManager = pdfManager;
    this.stream = stream;
    this.xref = new XRef(stream, pdfManager);
    this._pagePromises = [];
    this._version = null;
    const idCounters = {
      font: 0,
    };
    this._globalIdFactory = class {
      static getDocId() {