[ObjC ARC] Converts the rest of ios/web to ARC.

ios/web/web_state/web_state_delegate_bridge.mm

Index: ios/web/web_state/web_state_delegate_bridge.mm
diff --git a/ios/web/web_state/web_state_delegate_bridge.mm b/ios/web/web_state/web_state_delegate_bridge.mm
index acdc106374f6f5e8076bf72c62cc03c3c540ad85..c013d77f93981d963105c827955d145431fa50ce 100644
--- a/ios/web/web_state/web_state_delegate_bridge.mm
+++ b/ios/web/web_state/web_state_delegate_bridge.mm
@@ -7,6 +7,10 @@
 #include "base/logging.h"
 #import "ios/web/public/web_state/context_menu_params.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace web {
 
 WebStateDelegateBridge::WebStateDelegateBridge(id<CRWWebStateDelegate> delegate)
@@ -38,4 +42,4 @@ JavaScriptDialogPresenter* WebStateDelegateBridge::GetJavaScriptDialogPresenter(
   return nullptr;
 }
 
-}  // web
+}  // web