fix more 64bit warnings

BUG=skia:

Review URL: https://codereview.chromium.org/147683003

git-svn-id: http://skia.googlecode.com/svn/trunk@13190 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/ports/SkImageDecoder_CG.cpp b/src/ports/SkImageDecoder_CG.cpp
index beb6ed1..90c282d 100644
--- a/src/ports/SkImageDecoder_CG.cpp
+++ b/src/ports/SkImageDecoder_CG.cpp
@@ -66,8 +66,8 @@
     }
     SkAutoTCallVProc<CGImage, CGImageRelease> arimage(image);
 
-    const int width = CGImageGetWidth(image);
-    const int height = CGImageGetHeight(image);
+    const int width = SkToInt(CGImageGetWidth(image));
+    const int height = SkToInt(CGImageGetHeight(image));
     bm->setConfig(SkBitmap::kARGB_8888_Config, width, height);
     if (SkImageDecoder::kDecodeBounds_Mode == mode) {
         return true;