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
```
sink.close();
              return;
            }
            assert(
              isArrayBuffer(value),
              "GetRangeReader - expected an ArrayBuffer."
            );
            sink.enqueue(new Uint8Array(value), 1, [value]);
          })
          .catch(reason => {
            sink.error(reason);
          });
      };
      sink.onCancel = reason => {
        rangeReader.cancel(reason);
        sink.ready.catch(readyReason => {
          if (this.destroyed) {
            return; 
          }
          throw readyReason;
        });
      };
    });
    messageHandler.on("GetDoc", ({ pdfInfo }) => {
      this._numPages = pdfInfo.numPages;
      this._htmlForXfa = pdfInfo.htmlForXfa;
      delete pdfInfo.htmlForXfa;
      loadingTask._capability.resolve(new PDFDocumentProxy(pdfInfo, this));
    });
    messageHandler.on("DocException", function (ex) {