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 this.CMapReaderFactory.fetch(data);
    });
    messageHandler.on("FetchStandardFontData", data => {
      if (this.destroyed) {
        return Promise.reject(new Error("Worker was destroyed."));
      }
      if (!this.StandardFontDataFactory) {
        return Promise.reject(
          new Error(
            "StandardFontDataFactory not initialized, see the `useWorkerFetch` parameter."
          )
        );
      }
      return this.StandardFontDataFactory.fetch(data);
    });
  }
  _onUnsupportedFeature({ featureId }) {
    if (this.destroyed) {
      return; 
    }
    if (this.loadingTask.onUnsupportedFeature) {
      this.loadingTask.onUnsupportedFeature(featureId);
    }
  }
  getData() {
    return this.messageHandler.sendWithPromise("GetData", null);
  }
  getPage(pageNumber) {