fix warning from scalar --> int32 conversion

BUG=

Review URL: https://codereview.appspot.com/7065050

git-svn-id: http://skia.googlecode.com/svn/trunk@7061 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleAAClip.cpp b/samplecode/SampleAAClip.cpp
index 196641e..617d786 100644
--- a/samplecode/SampleAAClip.cpp
+++ b/samplecode/SampleAAClip.cpp
@@ -18,7 +18,7 @@
     c1.setRect(r1);
     c2.op(c0, c1, op);
 
-    SkIRect r2 = c2.getBounds();
+    SkDEBUGCODE(SkIRect r2 = c2.getBounds());
     SkASSERT(r2 == expectedR);
 }