Enable `as` based priorities for <link rel=preload>

Source/core/fetch/FetchRequest.h

Index: Source/core/fetch/FetchRequest.h
diff --git a/Source/core/fetch/FetchRequest.h b/Source/core/fetch/FetchRequest.h
index e2d8e576dc19d4b9d87df65aff824510b12c7c5f..5c690994188579350c272e2369eb6377acab6351 100644
--- a/Source/core/fetch/FetchRequest.h
+++ b/Source/core/fetch/FetchRequest.h
@@ -66,6 +66,7 @@ public:
     const ResourceLoaderOptions& options() const { return m_options; }
     void setOptions(const ResourceLoaderOptions& options) { m_options = options; }
     ResourceLoadPriority priority() const { return m_priority; }
+    void setPriority(ResourceLoadPriority priority) { m_priority = priority; }
     bool forPreload() const { return m_forPreload; }
     void setForPreload(bool forPreload) { m_forPreload = forPreload; }
     DeferOption defer() const { return m_defer; }