Fix BitmapCopy_Texture test on iOS

tests/BitmapCopyTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkRect.h"
 #include "Test.h"
@@ skipping 666 matching lines @@
                 desc.fFlags = rt ? kRenderTarget_GrSurfaceFlag : kNone_GrSurfaceFlags;
                 desc.fWidth = 2;
                 desc.fHeight = 2;
                 desc.fOrigin = kTopLeft_GrSurfaceOrigin;
 
                 const void* srcData = (kSkia8888_GrPixelConfig == desc.fConfig) ? kData : swizData;
 
                 SkAutoTUnref<GrTexture> texture(
                     ctx->textureProvider()->createTexture(desc, false, srcData, 0));
 
+                if (!texture) {
+                    continue;
+                }
+
                 SkBitmap srcBmp;
                 GrWrapTextureInBitmap(texture, 2, 2, false, &srcBmp);
                 if (srcBmp.isNull()) {
                     ERRORF(reporter, "Could not wrap texture in bitmap.");
                     continue;
                 }
                 static const SkColorType kDstCTs[] = { kRGBA_8888_SkColorType, kBGRA_8888_SkColorType };
                 for (size_t dCT = 0; dCT < SK_ARRAY_COUNT(kDstCTs); ++dCT) {
                     SkBitmap dstBmp;
                     if (!srcBmp.copyTo(&dstBmp, kDstCTs[dCT])) {
@@ skipping 24 matching lines @@
                         }
                         dstBmpPixels += dstBmp.rowBytes();
                     }
                 }
             }
         }
     }
 }
 
 #endif