remove deprecated use of porterduff enum



git-svn-id: http://skia.googlecode.com/svn/trunk@235 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/SkPorterDuff.cpp b/src/effects/SkPorterDuff.cpp
index 42f93b8..f3f598b 100644
--- a/src/effects/SkPorterDuff.cpp
+++ b/src/effects/SkPorterDuff.cpp
@@ -45,6 +45,13 @@
     return false;
 }
 
+SkXfermode::Mode SkPorterDuff::ToXfermodeMode(Mode mode) {
+    SkASSERT((unsigned)mode < SkPorterDuff::kModeCount);
+    const Pair& pair = gPairs[mode];
+    SkASSERT(pair.fPD == mode);
+    return pair.fXF;
+}
+
 SkXfermode* SkPorterDuff::CreateXfermode(SkPorterDuff::Mode mode) {
     const Pair& pair = gPairs[mode];
     SkASSERT(pair.fPD == mode);