Revert of change all factories to return their base-class

include/effects/SkXfermodeImageFilter.h

Index: include/effects/SkXfermodeImageFilter.h
diff --git a/include/effects/SkXfermodeImageFilter.h b/include/effects/SkXfermodeImageFilter.h
index d59b7a2b257c3d002b4ec10d03ba312b1685c782..57fd288f24f7c9d7313e33aea66b8efe6d6c7172 100644
--- a/include/effects/SkXfermodeImageFilter.h
+++ b/include/effects/SkXfermodeImageFilter.h
@@ -23,9 +23,9 @@
 public:
     virtual ~SkXfermodeImageFilter();
 
-    static SkImageFilter* Create(SkXfermode* mode, SkImageFilter* background,
-                                 SkImageFilter* foreground = NULL,
-                                 const CropRect* cropRect = NULL) {
+    static SkXfermodeImageFilter* Create(SkXfermode* mode, SkImageFilter* background,
+                                         SkImageFilter* foreground = NULL,
+                                         const CropRect* cropRect = NULL) {
         SkImageFilter* inputs[2] = { background, foreground };
         return new SkXfermodeImageFilter(mode, inputs, cropRect);
     }