Syntax highlighting not working for private fields

[TimvdLippe]

Private fields (https://v8.dev/features/class-fields) use a # at the start of the field declaration in a class. CodeMirror currently doesn't highlight these private fields as fields and its syntax highlighting marks the whole line as red. Example

class Project {
  #id;
  
  constructor(name) {
    this.name = name;
    this.#id = Math.random();
  }
  
  get id() {
      return this.#id;
  }

  #setId(id) {
      this.#id = id;
  }

  aMethod() {}

  static fromStore(id, name) {
      const proj = new Project(name);
      proj.#setId(id);
      proj.aMethod();
      return proj; 
  }
}

Current syntax highlighting:

(Code was pasted on https://codemirror.net/mode/javascript/index.html)

The expected syntax highlighting here is that private fields have the same color as normal fields (e.g. name in this example).

Downstream issue: https://bugs.chromium.org/p/chromium/issues/detail?id=1073903

[TimvdLippe]

Thanks for fixing this so quickly!