Relocate the specialized linear gradient interval builder

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 1eeb6c2f0f7573a58872e5a47f5be4ed033f3022..1e65308f69402d67be3304f1de28c37c1aa5e950 100644
--- a/src/effects/gradients/Sk4fGradientBase.h
+++ b/src/effects/gradients/Sk4fGradientBase.h
@@ -42,8 +42,6 @@ protected:
         bool     fZeroRamp;
     };
 
-    const Interval* findInterval(SkScalar fx) const;
-
     SkSTArray<8, Interval, true> fIntervals;
     SkMatrix                     fDstToPos;
     SkMatrix::MapXYProc          fDstToPosProc;
@@ -54,11 +52,6 @@ protected:
 
 private:
     using INHERITED = SkShader::Context;
-
-    void addMirrorIntervals(const SkGradientShaderBase&, const Sk4f& componentScale,
-                            bool dx_is_pos);
-
-    mutable const Interval*      fCachedInterval;
 };
 
 #endif // Sk4fGradientBase_DEFINED