Dynamically create stencil buffer when needed.

src/effects/SkGpuBlurUtils.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGpuBlurUtils.h"
 
 #include "SkRect.h"
@@ skipping 149 matching lines @@
     scale_rect(&srcRect, static_cast<float>(scaleFactorX),
                          static_cast<float>(scaleFactorY));
 
     GrContext::AutoClip acs(context, SkRect::MakeWH(srcRect.width(), srcRect.height()));
 
     SkASSERT(kBGRA_8888_GrPixelConfig == srcTexture->config() ||
              kRGBA_8888_GrPixelConfig == srcTexture->config() ||
              kAlpha_8_GrPixelConfig == srcTexture->config());
 
     GrSurfaceDesc desc;
-    desc.fFlags = kRenderTarget_GrSurfaceFlag | kNoStencil_GrSurfaceFlag;
+    desc.fFlags = kRenderTarget_GrSurfaceFlag;
     desc.fWidth = SkScalarFloorToInt(srcRect.width());
     desc.fHeight = SkScalarFloorToInt(srcRect.height());
     desc.fConfig = srcTexture->config();
 
     GrTexture* dstTexture;
     GrTexture* tempTexture;
     SkAutoTUnref<GrTexture> temp1, temp2;
 
     temp1.reset(context->refScratchTexture(desc, GrContext::kApprox_ScratchTexMatch));
     dstTexture = temp1.get();
@@ skipping 112 matching lines @@
                                      srcRect);
         srcRect = dstRect;
         srcTexture = dstTexture;
         SkTSwap(dstTexture, tempTexture);
     }
     return SkRef(srcTexture);
 }
 #endif
 
 }