Small cleanup in webView:didCommitNavigation:.

Use existing currentWKItemURL variable instead of
net::GURLWithNSURL(webView.backForwardList.currentItem.URL)

Bug: None
Change-Id: If84aca1551f43d6ccfc36eb404213967148cb030
Reviewed-on: https://chromium-review.googlesource.com/c/1329890Reviewed-by: Danyao Wang <danyao@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606950}

ios/web/web_state/ui/crw_web_controller.mm

@@ -4793,7 +4793,7 @@ registerLoadRequestForURL:(const GURL&)requestURL
     // It is possible for |webView.URL| to be nil, in which case
     // webView.backForwardList.currentItem.URL will return the right committed
     // URL (crbug.com/784480).
-    webViewURL = net::GURLWithNSURL(webView.backForwardList.currentItem.URL);
+    webViewURL = currentWKItemURL;
   } else if (context && context->GetUrl() == currentWKItemURL) {
     // If webView.backForwardList.currentItem.URL matches |context|, then this
     // is a known edge case where |webView.URL| is wrong.