Basic implementation of <import>

sky/engine/core/fetch/FetchRequest.h

Index: sky/engine/core/fetch/FetchRequest.h
diff --git a/sky/engine/core/fetch/FetchRequest.h b/sky/engine/core/fetch/FetchRequest.h
index a94b68185bcc43e9f1092cfdac3e8d4fd2035b56..3a69a6743b0b1f222c066689ab9d5d30058fc06b 100644
--- a/sky/engine/core/fetch/FetchRequest.h
+++ b/sky/engine/core/fetch/FetchRequest.h
@@ -40,7 +40,7 @@ public:
     enum DeferOption { NoDefer, DeferredByClient };
     enum OriginRestriction { UseDefaultOriginRestrictionForType, RestrictToSameOrigin, NoOriginRestriction };
 
-    explicit FetchRequest(const ResourceRequest&, const AtomicString& initiator, const String& charset = String(), ResourceLoadPriority = ResourceLoadPriorityUnresolved);
+    explicit FetchRequest(const ResourceRequest&, const AtomicString& initiator = AtomicString(), const String& charset = String(), ResourceLoadPriority = ResourceLoadPriorityUnresolved);
     FetchRequest(const ResourceRequest&, const AtomicString& initiator, const ResourceLoaderOptions&);
     FetchRequest(const ResourceRequest&, const FetchInitiatorInfo&);
     ~FetchRequest();