Fix a warning.

git-svn-id: http://skia.googlecode.com/svn/trunk/src@11489 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/utils/SkFrontBufferedStream.cpp b/utils/SkFrontBufferedStream.cpp
index 12030da..d68b9e4 100644
--- a/utils/SkFrontBufferedStream.cpp
+++ b/utils/SkFrontBufferedStream.cpp
@@ -138,7 +138,7 @@
     }
 
     if (size > 0 && !fStream->isAtEnd()) {
-        const size_t bytesReadDirectly = this->readDirectlyFromStream(dst, size);
+        SkDEBUGCODE(const size_t bytesReadDirectly =) this->readDirectlyFromStream(dst, size);
         SkDEBUGCODE(size -= bytesReadDirectly;)
         SkASSERT(size + (fOffset - start) == totalSize);
     }