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
```
let reason;
      switch (ex.name) {
        case "PasswordException":
          reason = new PasswordException(ex.message, ex.code);
          break;
        case "InvalidPDFException":
          reason = new InvalidPDFException(ex.message);
          break;
        case "MissingPDFException":
          reason = new MissingPDFException(ex.message);
          break;
        case "UnexpectedResponseException":
          reason = new UnexpectedResponseException(ex.message, ex.status);
          break;
        case "UnknownErrorException":
          reason = new UnknownErrorException(ex.message, ex.details);
          break;
      }
      if (!(reason instanceof Error)) {
        const msg = "DocException - expected a valid Error.";
        if (
          typeof PDFJSDev === "undefined" ||
          PDFJSDev.test("!PRODUCTION || TESTING")
        ) {
          unreachable(msg);
        } else {
          warn(msg);
        }
      }
      loadingTask._capability.reject(reason);