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
```
}
    if (!Array.isArray(xfa) || xfa.length === 0) {
      return null;
    }
    for (let i = 0, ii = xfa.length; i < ii; i += 2) {
      let name;
      if (i === 0) {
        name = "xdp:xdp";
      } else if (i === ii - 2) {
        name = "/xdp:xdp";
      } else {
        name = xfa[i];
      }
      if (!entries.hasOwnProperty(name)) {
        continue;
      }
      const data = this.xref.fetchIfRef(xfa[i + 1]);
      if (!isStream(data) || data.isEmpty) {
        continue;
      }
      try {
        entries[name] = stringToUTF8String(data.getString());
      } catch (_) {
        warn("XFA - Invalid utf-8 string.");
        return null;
      }
    }
    return entries;
  }
  get xfaFactory() {