effects: Replaces uses of GrAssert with SkASSERT.

This is the first step on migrating from GrAssert to SkASSERT as requested by
Brian.

R=bsalomon@google.com, robertphillips@google.com, scroggo@google.com

Author: tfarina@chromium.org

Review URL: https://chromiumcodereview.appspot.com/22418006

git-svn-id: http://skia.googlecode.com/svn/trunk@10706 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/SkArithmeticMode.cpp b/src/effects/SkArithmeticMode.cpp
index 43c62ec..ed29130 100644
--- a/src/effects/SkArithmeticMode.cpp
+++ b/src/effects/SkArithmeticMode.cpp
@@ -364,7 +364,7 @@
         dstColor = builder->dstColor();
     }
 
-    GrAssert(NULL != dstColor);
+    SkASSERT(NULL != dstColor);
     fKUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
                                 kVec4f_GrSLType, "k");
     const char* kUni = builder->getUniformCStr(fKUni);