only report hasspan16 if we're opaque, otherwise we get a different blend

via 565 than the 8888 case



git-svn-id: http://skia.googlecode.com/svn/trunk@527 2bbb7eff-a529-9590-31e7-b0007b416f81

src/core/SkShader.cpp

@@ -263,11 +263,11 @@ bool SkColorShader::setContext(const SkBitmap& device, const SkPaint& paint,
     fPMColor = SkPackARGB32(a, r, g, b);
 
     fFlags = kConstInY32_Flag;
-    if (paint.isDither() == false) {
-        fFlags |= kHasSpan16_Flag;
-    }
-    if (SkGetPackedA32(fPMColor) == 255) {
+    if (255 == a) {
         fFlags |= kOpaqueAlpha_Flag;
+        if (paint.isDither() == false) {
+            fFlags |= kHasSpan16_Flag;
+        }
     }
 
     return true;