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 fnArray[i] === OPS.paintImageMaskXObject;
      case 3:
        return fnArray[i] === OPS.restore;
    }
    throw new Error(`iterateImageMaskGroup - invalid pos: ${pos}`);
  },
  function foundImageMaskGroup(context, i) {
    const MIN_IMAGES_IN_MASKS_BLOCK = 10;
    const MAX_IMAGES_IN_MASKS_BLOCK = 100;
    const MAX_SAME_IMAGES_IN_MASKS_BLOCK = 1000;
    const fnArray = context.fnArray,
      argsArray = context.argsArray;
    const curr = context.iCurr;
    const iFirstSave = curr - 3;
    const iFirstTransform = curr - 2;
    const iFirstPIMXO = curr - 1;
    
    
    let count = Math.floor((i - iFirstSave) / 4);
    count = handlePaintSolidColorImageMask(
      iFirstSave,
      count,
      fnArray,
      argsArray
    );
    if (count < MIN_IMAGES_IN_MASKS_BLOCK) {
      return i - ((i - iFirstSave) % 4);
    }
    let isSameImage = false;
    let iTransform, transformArgs;