4f gradient interval builder cleanup

src/effects/gradients/Sk4fGradientBase.h

Index: src/effects/gradients/Sk4fGradientBase.h
diff --git a/src/effects/gradients/Sk4fGradientBase.h b/src/effects/gradients/Sk4fGradientBase.h
index 7870bc3ccf3a550809ccc54c336bb673593e2274..1eeb6c2f0f7573a58872e5a47f5be4ed033f3022 100644
--- a/src/effects/gradients/Sk4fGradientBase.h
+++ b/src/effects/gradients/Sk4fGradientBase.h
@@ -55,6 +55,9 @@ protected:
 private:
     using INHERITED = SkShader::Context;
 
+    void addMirrorIntervals(const SkGradientShaderBase&, const Sk4f& componentScale,
+                            bool dx_is_pos);
+
     mutable const Interval*      fCachedInterval;
 };