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 !!(flags & flag);
  }
  /**
   * @private
   */
  _isViewable(flags) {
    return (
      !this._hasFlag(flags, AnnotationFlag.INVISIBLE) &&
      !this._hasFlag(flags, AnnotationFlag.NOVIEW)
    );
  }
  /**
   * @private
   */
  _isPrintable(flags) {
    return (
      this._hasFlag(flags, AnnotationFlag.PRINT) &&
      !this._hasFlag(flags, AnnotationFlag.INVISIBLE)
    );
  }
  /**
   * Check if the annotation must be displayed by taking into account
   * the value found in the annotationStorage which may have been set
   * through JS.
   *
   * @public
   * @memberof Annotation
   * @param {AnnotationStorage} [annotationStorage] - Storage for annotation
   */
  mustBeViewed(annotationStorage) {