Fix more VS2010 warnings.

Review URL: http://codereview.appspot.com/5169053/



git-svn-id: http://skia.googlecode.com/svn/trunk@2432 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/experimental/SkSetPoly3To3_D.cpp b/experimental/SkSetPoly3To3_D.cpp
index 29526c9..810e6b2 100644
--- a/experimental/SkSetPoly3To3_D.cpp
+++ b/experimental/SkSetPoly3To3_D.cpp
@@ -11,7 +11,7 @@
 
 static SkScalar SkDScalar_toScalar(SkDScalar value) {
     SkDScalar result = (value + (1 << 15)) >> 16;
-    int top = result >> 31;
+    SkDEBUGCODE(int top = static_cast<int>(result >> 31);)
     SkASSERT(top == 0 || top == -1);
     return (SkScalar)result;
 }