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
```
if (renderForms && !(this instanceof SignatureWidgetAnnotation)) {
      return Promise.resolve(new OperatorList());
    }
    if (!this._hasText) {
      return super.getOperatorList(
        evaluator,
        task,
        renderForms,
        annotationStorage
      );
    }
    return this._getAppearance(evaluator, task, annotationStorage).then(
      content => {
        if (this.appearance && content === null) {
          return super.getOperatorList(
            evaluator,
            task,
            renderForms,
            annotationStorage
          );
        }
        const operatorList = new OperatorList();
        
        
        if (!this._defaultAppearance || content === null) {
          return operatorList;