Added implementation for provisional failure handling method for WkWebview. (#12327) fixes #12312 fixes #12732

Author: aaRopi

Xamarin.Forms.Platform.iOS/Renderers/WkWebViewRenderer.cs

@@ -664,6 +664,16 @@ public override void DidFailNavigation(WKWebView webView, WKNavigation navigatio
 				_renderer.UpdateCanGoBackForward();
 			}
 
+			public override void DidFailProvisionalNavigation(WKWebView webView, WKNavigation navigation, NSError error)
+			{
+				var url = GetCurrentUrl();
+				WebView.SendNavigated(
+					new WebNavigatedEventArgs(_lastEvent, new UrlWebViewSource { Url = url }, url, WebNavigationResult.Failure)
+				);
+
+				_renderer.UpdateCanGoBackForward();
+			}
+
 			public override void DidFinishNavigation(WKWebView webView, WKNavigation navigation)
 			{
 				if (webView.IsLoading)