Introduce Promises.

Source/core/dom/Promise.h

Index: Source/core/dom/Promise.h
diff --git a/Source/core/loader/UniqueIdentifier.cpp b/Source/core/dom/Promise.h
similarity index 87%
copy from Source/core/loader/UniqueIdentifier.cpp
copy to Source/core/dom/Promise.h
index 0ad56563e3e214a67acd8c53decb085ad4250cb9..2c842aa4c117365f9c564c21d18cf38dc6a1a6d4 100644
--- a/Source/core/loader/UniqueIdentifier.cpp
+++ b/Source/core/dom/Promise.h
@@ -28,17 +28,19 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "config.h"
-#include "core/loader/UniqueIdentifier.h"
+// FIXME: This file should be deleted.
+#ifndef Promise_h
+#define Promise_h
 
-namespace WebCore {
+#include "wtf/RefCounted.h"
 
-static unsigned long s_uniqueIdentifier = 0;
+namespace WebCore {
 
-unsigned long createUniqueIdentifier()
-{
-    return ++s_uniqueIdentifier;
-}
+// An empty class. This is here because a generated file use it.
+class Promise : public RefCounted<Promise> {
+};
 
 } // namespace WebCore
 
+
+#endif // Promise_h