Add two classes [as yet unused] needed for upcoming IDB Blob support.

Source/platform/exported/WebBlobInfo.cpp

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "public/platform/WebBlobInfo.h"
+
+#include "platform/blob/BlobInfo.h"
+
+namespace blink {
+
+WebBlobInfo::operator WebCore::BlobInfo() const
+{
+    if (isFile())
+        return WebCore::BlobInfo(uuid(), filePath(), fileName(), type(), lastModified(), size());
+    return WebCore::BlobInfo(uuid(), type(), size());
+}
+
+} // namespace blink