How do I get uri to localstorage file in windows phone 8.1 app

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C#

Windows

phone

In my app I need to download an html page to be displayed in a WebView controll. I have seen the tutorial where I load an html file stored in solituion folder, but I need to display the file from a localStorage folder like this:

ApplicationData.Current.LocalFolder.GetFolderAsync("HtmFolder");
var file = await localFolder.GetFileAsync("index.html");

Both the file and the folder exists.
So how can I display index.html in a WebView control?

What I have tried:

I have tried this, but I dont know what to put inside the uri:

Uri uri = Browser.BuildLocalStreamUri("MyTag", "file.Path"); // this throws an exception
var file = StorageFile.GetFileFromApplicationUriAsync(uri);
StreamUriWinRTResolver resolver = new StreamUriWinRTResolver();
Browser.NavigateToLocalStreamUri(uri, resolver);