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
```
if (this._useRequestAnimationFrame) {
        window.requestAnimationFrame(() => {
          this._nextBound().catch(this._cancelBound);
        });
      } else {
        Promise.resolve().then(this._nextBound).catch(this._cancelBound);
      }
    }
    async _next() {
      if (this.cancelled) {
        return;
      }
      this.operatorListIdx = this.gfx.executeOperatorList(
        this.operatorList,
        this.operatorListIdx,
        this._continueBound,
        this.stepper
      );
      if (this.operatorListIdx === this.operatorList.argsArray.length) {
        this.running = false;
        if (this.operatorList.lastChunk) {