Do really include the beacon Blob content type if valid.

Source/core/loader/BeaconLoader.cpp

Index: Source/core/loader/BeaconLoader.cpp
diff --git a/Source/core/loader/BeaconLoader.cpp b/Source/core/loader/BeaconLoader.cpp
index 82e10481e9b056bfab5de9875d226af3be72b232..17126db5ba9c6bc55d43dcff002217ddcef9f7e2 100644
--- a/Source/core/loader/BeaconLoader.cpp
+++ b/Source/core/loader/BeaconLoader.cpp
@@ -147,10 +147,9 @@ bool Beacon::serialize(Blob* data, ResourceRequest& request, int, int&)
 
     request.setHTTPBody(entityBody.release());
 
-    AtomicString contentType;
     const String& blobType = data->type();
     if (!blobType.isEmpty() && isValidContentType(blobType))
-        request.setHTTPContentType(AtomicString(contentType));
+        request.setHTTPContentType(AtomicString(blobType));
 
     return true;
 }