Introduce Stream::flush [1/2 blink]

Source/core/streams/Stream.h

Index: Source/core/streams/Stream.h
diff --git a/Source/core/streams/Stream.h b/Source/core/streams/Stream.h
index a0b8aff3b9e15734265e18736b0b98437c3afd34..0986b471afdbaed0cf120c841e6be93575390ecb 100644
--- a/Source/core/streams/Stream.h
+++ b/Source/core/streams/Stream.h
@@ -62,6 +62,8 @@ public:
 
     // Appends data to this stream.
     void addData(const char* data, size_t len);
+    // Flushes contents buffered in the stream.
+    void flush();
     // Mark this stream finalized so that a reader of this stream is notified
     // of EOF.
     void finalize();