LibWeb/HTML: Track secure context as part of Serialized{Document,Worker}

This is somewhat awkward as the spec refers to 'is secure context'
with respect to these objects 'relevant settings object'. A natural
way of implementing this could be storing a pointer to the relevant
settings object like the JS representations of these objects do
(and then changing is_secure_context to accept this representation
too), but for now it seems much simpler to just store a boolean for
this purpose and sidestep both problems above.

Libraries/LibWeb/HTML/Scripting/SerializedEnvironmentSettingsObject.h

@@ -22,6 +22,7 @@ enum class CanUseCrossOriginIsolatedAPIs : u8 {
 
 struct SerializedDocument {
     URL::URL url;
+    bool relevant_settings_object_is_secure_context { false };
 };
 
 struct SerializedWindow {
@@ -29,6 +30,7 @@ struct SerializedWindow {
 };
 
 struct SerializedWorkerGlobalScope {
+    bool relevant_settings_object_is_secure_context { false };
 };
 
 using SerializedGlobal = Variant<SerializedWindow, SerializedWorkerGlobalScope>;