[XHR] Ignore didReceiveData when having a DataConsumerHandle.

Source/core/loader/DocumentThreadableLoader.h

Index: Source/core/loader/DocumentThreadableLoader.h
diff --git a/Source/core/loader/DocumentThreadableLoader.h b/Source/core/loader/DocumentThreadableLoader.h
index 34af423ba6c2abc40bc797b7f7f59a8fba1fa729..5df617f683f8897c0c28ecb95843de46a3c1ba86 100644
--- a/Source/core/loader/DocumentThreadableLoader.h
+++ b/Source/core/loader/DocumentThreadableLoader.h
@@ -141,6 +141,10 @@ class CORE_EXPORT DocumentThreadableLoader final : public ThreadableLoader, priv
         // Set to true if the current request is cross-origin and not simple.
         bool m_crossOriginNonSimpleRequest;
 
+        // Set to true when the response data is given to a data consumer
+        // handle.
+        bool m_isUsingDataConsumerHandle;
+
         const bool m_async;
 
         // Holds the original request context (used for sanity checks).