It is dangerous to ignore SkRect::intersect's return value

gm/gmmain.cpp

Index: gm/gmmain.cpp
diff --git a/gm/gmmain.cpp b/gm/gmmain.cpp
index ece8ff32d4888f0d26cb2768df7c4ed5d7b118e6..1652e61f7c0d092378ae2ccce06177bb50861c77 100644
--- a/gm/gmmain.cpp
+++ b/gm/gmmain.cpp
@@ -704,8 +704,10 @@ public:
                 SkRect content = SkRect::MakeWH(SkIntToScalar(pageSize.width()),
                                                 SkIntToScalar(pageSize.height()));
                 initialTransform.mapRect(&content);
-                content.intersect(0, 0, SkIntToScalar(pageSize.width()),
-                                  SkIntToScalar(pageSize.height()));
+                if (!content.intersect(0, 0, SkIntToScalar(pageSize.width()),
+                                       SkIntToScalar(pageSize.height()))) {
+                    content.setEmpty();
+                }
                 SkISize contentSize =
                     SkISize::Make(SkScalarRoundToInt(content.width()),
                                   SkScalarRoundToInt(content.height()));