Add disableStencil method to GrGLGpu

src/gpu/gl/GrGLGpu.h

Index: src/gpu/gl/GrGLGpu.h
diff --git a/src/gpu/gl/GrGLGpu.h b/src/gpu/gl/GrGLGpu.h
index 0160835c6e4449d9282472611d0278fa3b35df89..29d20e4b6309011e26e81e5d6800e395760d9208 100644
--- a/src/gpu/gl/GrGLGpu.h
+++ b/src/gpu/gl/GrGLGpu.h
@@ -341,6 +341,7 @@ private:
     void flushViewport(const GrGLIRect&);
 
     void flushStencil(const GrStencilSettings&);
+    void disableStencil();
 
     // rt is used only if useHWAA is true.
     void flushHWAAState(GrRenderTarget* rt, bool useHWAA, bool stencilEnabled);