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
```
constructor(params) {
    super(params);
    this._hasText = true;
    const dict = params.dict;
    
    if (!isString(this.data.fieldValue)) {
      this.data.fieldValue = "";
    }
    
    let alignment = getInheritableProperty({ dict, key: "Q" });
    if (!Number.isInteger(alignment) || alignment < 0 || alignment > 2) {
      alignment = null;
    }
    this.data.textAlignment = alignment;
    
    let maximumLength = getInheritableProperty({ dict, key: "MaxLen" });
    if (!Number.isInteger(maximumLength) || maximumLength < 0) {
      maximumLength = null;
    }
    this.data.maxLen = maximumLength;
    
    this.data.multiLine = this.hasFieldFlag(AnnotationFieldFlag.MULTILINE);
    this.data.comb =
      this.hasFieldFlag(AnnotationFieldFlag.COMB) &&
      !this.hasFieldFlag(AnnotationFieldFlag.MULTILINE) &&
      !this.hasFieldFlag(AnnotationFieldFlag.PASSWORD) &&
      !this.hasFieldFlag(AnnotationFieldFlag.FILESELECT) &&
      this.data.maxLen !== null;
  }
  _getCombAppearance(defaultAppearance, font, text, width, hPadding, vPadding) {