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
```
return new LineAnnotation(parameters);
      case "Square":
        return new SquareAnnotation(parameters);
      case "Circle":
        return new CircleAnnotation(parameters);
      case "PolyLine":
        return new PolylineAnnotation(parameters);
      case "Polygon":
        return new PolygonAnnotation(parameters);
      case "Caret":
        return new CaretAnnotation(parameters);
      case "Ink":
        return new InkAnnotation(parameters);
      case "Highlight":
        return new HighlightAnnotation(parameters);
      case "Underline":
        return new UnderlineAnnotation(parameters);
      case "Squiggly":
        return new SquigglyAnnotation(parameters);
      case "StrikeOut":
        return new StrikeOutAnnotation(parameters);
      case "Stamp":
        return new StampAnnotation(parameters);
      case "FileAttachment":
        return new FileAttachmentAnnotation(parameters);
      default:
        if (!collectFields) {
          if (!subtype) {
            warn("Annotation is missing the required /Subtype.");
          } else {