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 customValue;
          if (isString(value)) {
            customValue = stringToPDFString(value);
          } else if (isName(value) || isNum(value) || isBool(value)) {
            customValue = value;
          } else {
            info(`Unsupported value in document info for (custom) "${key}".`);
            continue;
          }
          if (!docInfo.Custom) {
            docInfo.Custom = Object.create(null);
          }
          docInfo.Custom[key] = customValue;
        }
      }
    }
    return shadow(this, "documentInfo", docInfo);
  }
  get fingerprints() {
    function validate(data) {
      return (
        typeof data === "string" &&
        data.length > 0 &&
        data !== EMPTY_FINGERPRINT
      );
    }
    function hexString(hash) {