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
```
const mask = smask.canvas;
    const maskCtx = smask.context;
    ctx.setTransform(
      smask.scaleX,
      0,
      0,
      smask.scaleY,
      smask.offsetX,
      smask.offsetY
    );
    genericComposeSMask(
      maskCtx,
      layerCtx,
      mask.width,
      mask.height,
      smask.subtype,
      smask.backdrop,
      smask.transferMap
    );
    ctx.drawImage(mask, 0, 0);
  }
  const LINE_CAP_STYLES = ["butt", "round", "square"];
  const LINE_JOIN_STYLES = ["miter", "round", "bevel"];
  const NORMAL_CLIP = {};
  const EO_CLIP = {};
  
  class CanvasGraphics {
    constructor(