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
```
ctx.strokeStyle = "#000000";
    ctx.fillStyle = "#000000";
    ctx.fillRule = "nonzero";
    ctx.globalAlpha = 1;
    ctx.lineWidth = 1;
    ctx.lineCap = "butt";
    ctx.lineJoin = "miter";
    ctx.miterLimit = 10;
    ctx.globalCompositeOperation = "source-over";
    ctx.font = "10px sans-serif";
    if (ctx.setLineDash !== undefined) {
      ctx.setLineDash([]);
      ctx.lineDashOffset = 0;
    }
  }
  function composeSMaskBackdrop(bytes, r0, g0, b0) {