Mark BackgroundImageGeometry as stack allocated

BUG=521481

Review URL: https://codereview.chromium.org/1297913003

git-svn-id: svn://svn.chromium.org/blink/trunk@200715 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/paint/BackgroundImageGeometry.h

@@ -8,10 +8,12 @@
 #include "platform/geometry/IntPoint.h"
 #include "platform/geometry/IntRect.h"
 #include "platform/geometry/IntSize.h"
+#include "wtf/Allocator.h"
 
 namespace blink {
 
 class BackgroundImageGeometry {
+    STACK_ALLOCATED();
 public:
     BackgroundImageGeometry()
         : m_hasNonLocalGeometry(false)