Implement `github_actrnuf` with Dart

highlight.dart

import 'dart:html';

void classifyDate(Element modified_at) {
    RegExp more_a_year = new RegExp("year");
    RegExp more_5_month = new RegExp("([5-9]|1)+ months");
    if (more_a_year.hasMatch(modified_at.text)) {
      modified_at.style.color = 'red';
    }else if (more_5_month.hasMatch(modified_at.text)) {
      modified_at.style.color = 'orange';
    }
}

void main() {
  ElementList modified_date = document.querySelectorAll("time[is='time-ago']");
  modified_date.forEach((Element modified_at) {
    classifyDate(modified_at);
  });
}