Disable gpu-side clip mask merging in the clip mask manager

src/gpu/GrClipMaskManager.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef GrClipMaskManager_DEFINED
 #define GrClipMaskManager_DEFINED
 
 #include "GrPipelineBuilder.h"
@@ skipping 115 matching lines @@
 
     // Draws a clip element into the target alpha mask. The caller should have already setup the
     // desired blend operation. Optionally if the caller already selected a path renderer it can
     // be passed. Otherwise the function will select one if the element is a path.
     bool drawElement(GrPipelineBuilder*,
                      const SkMatrix& viewMatrix,
                      GrTexture* target,
                      const SkClipStack::Element*,
                      GrPathRenderer* pr = nullptr);
 
-    // Determines whether it is possible to draw the element to both the stencil buffer and the
-    // alpha mask simultaneously. If so and the element is a path a compatible path renderer is
-    // also returned.
-    bool canStencilAndDrawElement(GrPipelineBuilder*,
-                                  GrTexture* target,
-                                  GrPathRenderer**,
-                                  const SkClipStack::Element*);
-
     void mergeMask(GrPipelineBuilder*,
                    GrTexture* dstMask,
                    GrTexture* srcMask,
                    SkRegion::Op op,
                    const SkIRect& dstBound,
                    const SkIRect& srcBound);
 
     GrTexture* createTempMask(int width, int height);
 
     /**
@@ skipping 14 matching lines @@
     GrTexture* createCachedMask(int width, int height, const GrUniqueKey& key, bool renderTarget);
 
     static const int kMaxAnalyticElements = 4;
 
     GrDrawTarget*   fDrawTarget;    // This is our owning draw target.
     StencilClipMode fClipMode;
 
     typedef SkNoncopyable INHERITED;
 };
 #endif // GrClipMaskManager_DEFINED