[ios] Signal DidFinishLoad if target URL is invalid.

ios/web/web_state/ui/crw_web_controller.mm

Index: ios/web/web_state/ui/crw_web_controller.mm
diff --git a/ios/web/web_state/ui/crw_web_controller.mm b/ios/web/web_state/ui/crw_web_controller.mm
index 9b38ec19842be9aa97bf10bc49239b45f409431f..6b62be6d4b32df3bd508786552e08d9b25ee1220 100644
--- a/ios/web/web_state/ui/crw_web_controller.mm
+++ b/ios/web/web_state/ui/crw_web_controller.mm
@@ -1327,8 +1327,10 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
   // Load the url. The UIWebView delegate callbacks take care of updating the
   // session history and UI.
   const GURL targetURL([self currentNavigationURL]);
-  if (!targetURL.is_valid())
+  if (!targetURL.is_valid()) {
+    [self didFinishWithURL:targetURL loadSuccess:NO];
     return;
+  }
 
   // JavaScript should never be evaluated here. User-entered JS should be
   // evaluated via stringByEvaluatingUserJavaScriptFromString.