experiment: float color components

src/core/SkShader.cpp

Index: src/core/SkShader.cpp
diff --git a/src/core/SkShader.cpp b/src/core/SkShader.cpp
index bd3876a69b988a0d329e7e1e9abed02052223d12..5f3319857251181c79ec79fbb8c424d2e08fc712 100644
--- a/src/core/SkShader.cpp
+++ b/src/core/SkShader.cpp
@@ -117,6 +117,10 @@ SkShader::Context::ShadeProc SkShader::Context::asAShadeProc(void** ctx) {
     return nullptr;
 }
 
+void SkShader::Context::shadeSpan4f(int x, int y, SkPM4f[], int count) {
+    SkASSERT(!"shadeSpan4f called but not implemented");
+}
+
 #include "SkColorPriv.h"
 
 #define kTempColorQuadCount 6   // balance between speed (larger) and saving stack-space