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(params) {
    const dict = params.dict;
    this.setContents(dict.get("Contents"));
    this.setModificationDate(dict.get("M"));
    this.setFlags(dict.get("F"));
    this.setRectangle(dict.getArray("Rect"));
    this.setColor(dict.getArray("C"));
    this.setBorderStyle(dict);
    this.setAppearance(dict);
    this._streams = [];
    if (this.appearance) {
      this._streams.push(this.appearance);
    }
    
    this.data = {
      annotationFlags: this.flags,
      borderStyle: this.borderStyle,
      color: this.color,
      contents: this.contents,
      hasAppearance: !!this.appearance,
      id: params.id,
      modificationDate: this.modificationDate,
      rect: this.rectangle,
      subtype: params.subtype,
    };