Re-set referrer on issuing a validation request for a cached resource.

Source/core/fetch/ResourceFetcher.cpp

Index: Source/core/fetch/ResourceFetcher.cpp
diff --git a/Source/core/fetch/ResourceFetcher.cpp b/Source/core/fetch/ResourceFetcher.cpp
index 6b6e2d250ab29aaaf4037b95b9fb923e41c889bc..ce1e1845ab6ad706bd4356282886e5aee880fa92 100644
--- a/Source/core/fetch/ResourceFetcher.cpp
+++ b/Source/core/fetch/ResourceFetcher.cpp
@@ -780,6 +780,7 @@ ResourcePtr<Resource> ResourceFetcher::revalidateResource(const FetchRequest& re
     ASSERT(!resource->resourceToRevalidate());
 
     ResourceRequest revalidatingRequest(resource->resourceRequest());
+    revalidatingRequest.clearHTTPReferrer();
     addAdditionalRequestHeaders(revalidatingRequest, resource->type());
 
     const AtomicString& lastModified = resource->response().httpHeaderField("Last-Modified");