Convert ios_web_view_shell to pure Objective-C.

ios/web_view/shell/shell_exe_main.mm

Index: ios/web_view/shell/shell_exe_main.mm
diff --git a/ios/web_view/shell/shell_exe_main.mm b/ios/web_view/shell/shell_exe_main.mm
deleted file mode 100644
index 991f337c0a3d7464e6ddbeabc391c672fde964b8..0000000000000000000000000000000000000000
--- a/ios/web_view/shell/shell_exe_main.mm
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright 2014 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 "ios/web_view/shell/shell_app_delegate.h"
-
-#if !defined(__has_feature) || !__has_feature(objc_arc)
-#error "This file requires ARC support."
-#endif
-
-int main(int argc, char* argv[]) {
-  @autoreleasepool {
-    return UIApplicationMain(argc, argv, nil,
-                             NSStringFromClass([ShellAppDelegate class]));
-  }
-}