Account for alpha in hasShadow()

bug:17587220
Change-Id: Ic7f2dea95302b713dc93edb4a0193a7be77fb2eb
diff --git a/libs/hwui/RenderProperties.h b/libs/hwui/RenderProperties.h
index 46eeb6a..b936d4b 100644
--- a/libs/hwui/RenderProperties.h
+++ b/libs/hwui/RenderProperties.h
@@ -570,7 +570,9 @@
     }
 
     bool hasShadow() const {
-        return getZ() >= 0.0f && getOutline().getPath() != NULL;
+        return getZ() >= 0.0f
+                && getOutline().getPath() != NULL
+                && getOutline().getAlpha() != 0.0f;
     }
 
 private: