Add dest type hint to SkShader::ContextRec

src/core/SkDraw.cpp

Index: src/core/SkDraw.cpp
diff --git a/src/core/SkDraw.cpp b/src/core/SkDraw.cpp
index d42a179a94b3ba4bd5e19fd94c2028e449b086ee..a3d23a32381b1d0831ede0730c39b4b3b6e993d7 100644
--- a/src/core/SkDraw.cpp
+++ b/src/core/SkDraw.cpp
@@ -1895,7 +1895,8 @@ void SkDraw::drawVertices(SkCanvas::VertexMode vmode, int count,
             if (textures) {
                 SkMatrix tempM;
                 if (texture_to_matrix(state, vertices, textures, &tempM)) {
-                    SkShader::ContextRec rec(p, *fMatrix, &tempM);
+                    SkShader::ContextRec rec(p, *fMatrix, &tempM,
+                                             SkBlitter::PreferredShaderDest(fDst.info()));
                     if (!blitter->resetShaderContext(rec)) {
                         continue;
                     }