src/vs/base/common/strings.ts/CodePointIterator/nextCodePoint
class CodePointIterator:	public nextCodePoint(): number {
		const codePoint = getNextCodePoint(this._str, this._len, this._offset);
		this._offset += (codePoint >= Constants.UNICODE_SUPPLEMENTARY_PLANE_BEGIN ? 2 : 1);
		return codePoint;
	}