Remove ability for Release code to call getRefCnt() or getWeakRefCnt().

include/core/SkImageFilter.h

Index: include/core/SkImageFilter.h
diff --git a/include/core/SkImageFilter.h b/include/core/SkImageFilter.h
index ea882537c1b7acdb631dd76112dddd257e6adf99..a571184aa21bb66c4bc38b4b2eeca942245e4931 100644
--- a/include/core/SkImageFilter.h
+++ b/include/core/SkImageFilter.h
@@ -51,6 +51,7 @@ public:
     class SK_API Cache : public SkRefCnt {
     public:
         // By default, we cache only image filters with 2 or more children.
+        // Values less than 2 mean always cache; values greater than 2 are not supported.
         static Cache* Create(int minChildren = 2);
         virtual ~Cache() {}
         virtual bool get(const SkImageFilter* key, SkBitmap* result, SkIPoint* offset) = 0;