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
```
this.docBaseUrl = params.docBaseUrl || null;
      this.pdfDocument = {
        catalog: {
          acroForm: new Dict(),
        },
      };
    }
    ensure(obj, prop, args) {
      return new Promise(function (resolve) {
        const value = obj[prop];
        if (typeof value === "function") {
          resolve(value.apply(obj, args)
        } else {
          resolve(value