Attach (recommended) or Link to PDF file here: 

[anootation_problem.pdf](https://github.com/mozilla/pdf.js/files/7611701/anootation_problem.pdf)

Configuration:
- Web browser and its version: 98.0.4732.0 (Official Build) canary (64-bit)
- Operating system and its version: Edition Windows 10 Home, Version 20H2, OS build 19042.1348
- PDF.js version: 2.12.211
- Is a browser extension: Yes

Steps to reproduce the problem:
1. Open pdf file
2. Scroll to bottom of page and point to annotation of 'loss ft(x) >= 0,' text
3. Compare the displayed text with same in Acrobat Reader

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/2311076/143681452-0afa9a98-b16b-4a39-a393-631eb1c8c41f.png)

What went wrong? (add screenshot)
Text size not respected (e.g., in superscripts and subscripts)
![image](https://user-images.githubusercontent.com/2311076/143681575-2a2fe4de-cbad-4625-a6fe-2212fa20b8f1.png)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):

const style = Object.create(null);
  if (!styleStr) {
    return style;
  }
  const original = Object.create(null);
  for (const [key, value] of styleStr.split(";").map(s => s.split(":", 2))) {
    const mapping = StyleMapping.get(key);
    if (mapping === "") {
      continue;
    }
    let newValue = value;
    if (mapping) {
      if (typeof mapping === "string") {
        newValue = mapping;
      } else {
        newValue = mapping(value, original);