CellMapperに楽天モバイルエリアを表示させるUserScript

// ==UserScript==
// @name     Cellmapper add RakutenMobile layer
// @version  1
// @grant    GM_addStyle
// @include  https://www.cellmapper.net/map*
// ==/UserScript==

// Cellmapperに楽天モバイル自社エリアを表示するユーザースクリプト。
// Chrome+Tampermonkey と Firefox+GreaseMonkey にて動作確認。

const add_rmi_layer = function(){
  setTimeout(function(){
  console.log('start');
  const map = window.map;
  console.log(map);
  const rmi = new ol.layer.Tile({
    source: new ol.source.XYZ({
      url: "https://gateway-api.global.rakuten.com/dsd/geoserver/mno_coverage_map/gwc/service/gmaps?LAYERS=mno_coverage_map:rmi&FORMAT=image/png&TRANSPARENT=TRUE&x={x}&y={y}&zoom={z}",
      projection: "EPSG:3857"
    })
  });
  map.addLayer(rmi);
  console.log('end');
  },3000);
}

addJS_Node (null, null, add_rmi_layer);

function addJS_Node (text, s_URL, funcToRun, runOnLoad) {
    // see: https://stackoverflow.com/questions/13485122/accessing-variables-from-greasemonkey-to-page-vice-versa/13485650#13485650
    var D                                   = document;
    var scriptNode                          = D.createElement ('script');
    if (runOnLoad) {
        scriptNode.addEventListener ("load", runOnLoad, false);
    }
    scriptNode.type                         = "text/javascript";
    if (text)       scriptNode.textContent  = text;
    if (s_URL)      scriptNode.src          = s_URL;
    if (funcToRun)  scriptNode.textContent  = '(' + funcToRun.toString() + ')()';

    var targ = D.getElementsByTagName ('head')[0] || D.body || D.documentElement;
    targ.appendChild (scriptNode);
}