Add SkShader::asShadeProc to fast-path the caller when the shader is fast
Review URL: https://codereview.appspot.com/6649055

git-svn-id: http://skia.googlecode.com/svn/trunk@5930 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/core/SkShader.cpp b/src/core/SkShader.cpp
index 97cca5f..2f1def6 100644
--- a/src/core/SkShader.cpp
+++ b/src/core/SkShader.cpp
@@ -103,6 +103,10 @@
     return false;
 }
 
+SkShader::ShadeProc SkShader::asAShadeProc(void** ctx) {
+    return NULL;
+}
+
 #include "SkColorPriv.h"
 
 void SkShader::shadeSpan16(int x, int y, uint16_t span16[], int count) {