Update fetch / loader classes to use OVERRIDE / FINAL when needed

Source/core/fetch/ResourceFetcher.h

Index: Source/core/fetch/ResourceFetcher.h
diff --git a/Source/core/fetch/ResourceFetcher.h b/Source/core/fetch/ResourceFetcher.h
index 468ef23a05a2a51fb742bc451255ec6beb93b24e..539855149776994be01181f5aabe2ff22d078c2b 100644
--- a/Source/core/fetch/ResourceFetcher.h
+++ b/Source/core/fetch/ResourceFetcher.h
@@ -74,7 +74,7 @@ enum CORSEnabled {
 // RefPtr<ResourceFetcher> for their lifetime (and will create one if they
 // are initialized without a Frame), so a Document can keep a ResourceFetcher
 // alive past detach if scripts still reference the Document.
-class ResourceFetcher : public RefCounted<ResourceFetcher>, public ResourceLoaderHost {
+class ResourceFetcher FINAL : public RefCounted<ResourceFetcher>, public ResourceLoaderHost {
     WTF_MAKE_NONCOPYABLE(ResourceFetcher); WTF_MAKE_FAST_ALLOCATED;
 friend class ImageLoader;
 friend class ResourceCacheValidationSuppressor;