More win64 warning fixes

Review URL: https://codereview.chromium.org/798723002
diff --git a/gm/tallstretchedbitmaps.cpp b/gm/tallstretchedbitmaps.cpp
index 905cee8..db55ddd 100644
--- a/gm/tallstretchedbitmaps.cpp
+++ b/gm/tallstretchedbitmaps.cpp
@@ -69,7 +69,7 @@
 
     void onOnceBeforeDraw() SK_OVERRIDE {
         for (size_t i = 0; i < SK_ARRAY_COUNT(fTallBmps); ++i) {
-            int h = (4 + i) * 1024;
+            int h = SkToInt((4 + i) * 1024);
 
             fTallBmps[i].fItemCnt = make_bm(&fTallBmps[i].fBmp, h);
         }