Fix win7 BitmapTest

BUG=
R=bungeman@google.com

Review URL: https://codereview.chromium.org/110223005

git-svn-id: http://skia.googlecode.com/svn/trunk@12675 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/BitmapTest.cpp b/tests/BitmapTest.cpp
index a6859fa..250b6da 100644
--- a/tests/BitmapTest.cpp
+++ b/tests/BitmapTest.cpp
@@ -24,7 +24,7 @@
             if (setConf) {
                 REPORTER_ASSERT(reporter, bm.allocPixels(NULL));
             }
-            REPORTER_ASSERT(reporter, (width & height) != bm.empty());
+            REPORTER_ASSERT(reporter, SkToBool(width & height) != bm.empty());
         }
     }
 }