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/SampleRegion.cpp b/samplecode/SampleRegion.cpp
index 8b3a03c..b493ee4 100644
--- a/samplecode/SampleRegion.cpp
+++ b/samplecode/SampleRegion.cpp
@@ -274,13 +274,13 @@
 
             {
                 char    buffer[1000];
-                size_t  size = tmp.writeToMemory(NULL);
+                SkDEBUGCODE(size_t  size = ) tmp.writeToMemory(NULL);
                 SkASSERT(size <= sizeof(buffer));
-                size_t  size2 = tmp.writeToMemory(buffer);
+                SkDEBUGCODE(size_t  size2 = ) tmp.writeToMemory(buffer);
                 SkASSERT(size == size2);
 
                 SkRegion    tmp3;
-                size2 = tmp3.readFromMemory(buffer);
+                SkDEBUGCODE(size2 = ) tmp3.readFromMemory(buffer);
                 SkASSERT(size == size2);
 
                 SkASSERT(tmp3 == tmp);