Linux: Fix some NULL versus 0 issues to appease gcc-4.5.

webkit/glue/plugins/pepper_scrollbar.cc

Index: webkit/glue/plugins/pepper_scrollbar.cc
diff --git a/webkit/glue/plugins/pepper_scrollbar.cc b/webkit/glue/plugins/pepper_scrollbar.cc
index 48db8d40cbb5ea5357bb1fdd5db1e22fc24722eb..e6e691be38e49c6df299ce1e1fa9cab668eacd32 100644
--- a/webkit/glue/plugins/pepper_scrollbar.cc
+++ b/webkit/glue/plugins/pepper_scrollbar.cc
@@ -28,7 +28,7 @@ namespace {
 PP_Resource Create(PP_Instance instance_id, bool vertical) {
   PluginInstance* instance = PluginInstance::FromPPInstance(instance_id);
   if (!instance)
-    return NULL;
+    return 0;
 
   scoped_refptr<Scrollbar> scrollbar(new Scrollbar(instance, vertical));
   return scrollbar->GetReference();