Convert ios_web_shell_test to GN.

ios/web/shell/test/web_shell_navigation_egtest.mm

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import <UIKit/UIKit.h>
 #import <WebKit/WebKit.h>
 #import <XCTest/XCTest.h>
 
 #import <EarlGrey/EarlGrey.h>
 
 #include "base/strings/sys_string_conversions.h"
 #import "ios/web/public/test/http_server.h"
 #include "ios/web/public/test/http_server_util.h"
 #include "ios/web/shell/test/app/navigation_test_util.h"
 #include "ios/web/shell/test/app/web_view_interaction_test_util.h"
 #import "ios/web/shell/test/earl_grey/shell_base_test_case.h"
 #import "ios/web/shell/test/earl_grey/shell_matchers.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 // Navigation test cases for the web shell. These are Earl Grey integration
 // tests, which are based on XCTest.
 @interface CRWWebShellNavigationTest : ShellBaseTestCase
 
 @end
 
 @implementation CRWWebShellNavigationTest
 
 // Tests clicking a link to about:blank.
 - (void)testNavigationLinkToAboutBlank {
@@ skipping 142 matching lines @@
   web::shell_test_util::TapWebViewElementWithId("link");
 
   [[EarlGrey selectElementWithMatcher:web::addressFieldText(URL.spec())]
       assertWithMatcher:grey_notNil()];
   [[EarlGrey
       selectElementWithMatcher:web::webViewContainingText("No navigation!")]
       assertWithMatcher:grey_notNil()];
 }
 
 @end