How to inject userscript (IITC) into UWP WebView

MainPage.xaml

<Page
    x:Class="App1.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:App1"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <WebView x:Name="webView1" HorizontalAlignment="Center" Height="640" VerticalAlignment="Top"  
                 Source="https://www.ingress.com/intel/?vp=m" Width="360"
                  DOMContentLoaded="webView1_DOMContentLoaded" />

    </Grid>
</Page>

MainPage.xaml.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;

// 空白ページのアイテム テンプレートについては、http://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409 を参照してください

namespace App1
{
    /// <summary>
    /// それ自体で使用できる空白ページまたはフレーム内に移動できる空白ページ。
    /// </summary>
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
        }
        

        private async void webView1_DOMContentLoaded(WebView sender, WebViewDOMContentLoadedEventArgs args)
        {

            if (System.Text.RegularExpressions.Regex.IsMatch(
                webView1.Source.ToString(),
                @"ingress.com",
                System.Text.RegularExpressions.RegexOptions.ECMAScript))
            {
                System.Diagnostics.Debug.WriteLine("Site:intel, Continue to inject");
            }else {
                System.Diagnostics.Debug.WriteLine("Site:others: "+ webView1.Source.ToString());
                return;
            }

            var js = "u = ["
                + "'%R%total-conversion-build.user.js',"
                + "'%R%plugins/portal-highlighter-high-level.user.js',"
                + "'%R%plugins/player-tracker.user.js',"
                + "'%R%plugins/basemap-openstreetmap.user.js',"
                + "'%R%plugins/bookmarks-by-zaso.user.js',"
                + "'%R%plugins/sync.user.js',"
                + "'%R%plugins/draw-tools.user.js',"
                + "'%R%plugins/cross_link.user.js',"
                + "'%R%plugins/show-less-portals-zoomed-out.user.js',"
                + "'%R%plugins/score-cycle-times.user.js',"
                + "];"
                + "for(i in u){"
                + "s=document.createElement('script');"
                + "s.type='text/javascript';"
                + "s.src=u[i].replace('%R%','https://secure.jonatkins.com/iitc/release/');"
                + "document.getElementsByTagName('head')[0].appendChild(s);"
                + "};"
                +"(function(){return 'IITC Loaded!';})();";
            
            string result = await webView1.InvokeScriptAsync("eval", new string[] { js });
            System.Diagnostics.Debug.WriteLine(result);
        }
    }
}