LibWeb: Make PolicyContainer GC allocated

This is required to store Content Security Policies, as their
Directives are implemented as subclasses with overridden virtual
functions. Thus, they cannot be stored as generic Directive classes, as
it'll lose the ability to call overridden functions when they are
copied.

Libraries/LibWeb/HTML/Scripting/SerializedEnvironmentSettingsObject.h

@@ -10,7 +10,7 @@
 #include <LibIPC/Forward.h>
 #include <LibURL/Origin.h>
 #include <LibURL/URL.h>
-#include <LibWeb/HTML/PolicyContainers.h>
+#include <LibWeb/HTML/SerializedPolicyContainer.h>
 
 namespace Web::HTML {
 
@@ -28,7 +28,7 @@ struct SerializedEnvironmentSettingsObject {
     String api_url_character_encoding;
     URL::URL api_base_url;
     URL::Origin origin;
-    PolicyContainer policy_container;
+    SerializedPolicyContainer policy_container;
     CanUseCrossOriginIsolatedAPIs cross_origin_isolated_capability;
     double time_origin;
 };