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 {
      id: this.data.id,
      value: this.data.fieldValue,
      defaultValue: this.data.defaultFieldValue,
      multiline: this.data.multiLine,
      password: this.hasFieldFlag(AnnotationFieldFlag.PASSWORD),
      charLimit: this.data.maxLen,
      comb: this.data.comb,
      editable: !this.data.readOnly,
      hidden: this.data.hidden,
      name: this.data.fieldName,
      rect: this.data.rect,
      actions: this.data.actions,
      page: this.data.pageIndex,
      type: "text",
    };
  }
}
class ButtonWidgetAnnotation extends WidgetAnnotation {