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
```
assert(
      args.intent,
      'PDFPageProxy._pumpOperatorList: Expected "intent" argument.'
    );
    const readableStream = this._transport.messageHandler.sendWithStream(
      "GetOperatorList",
      args
    );
    const reader = readableStream.getReader();
    const intentState = this._intentStates.get(args.intent);
    intentState.streamReader = reader;
    const pump = () => {
      reader.read().then(
        ({ value, done }) => {
          if (done) {
            intentState.streamReader = null;
            return;
          }
          if (this._transport.destroyed) {
            return; 
          }
          this._renderPageChunk(value, intentState);
          pump();