Fix a crash in Pepper object scripting.

ppapi/proxy/ppb_var_deprecated_proxy.cc

Index: ppapi/proxy/ppb_var_deprecated_proxy.cc
===================================================================
--- ppapi/proxy/ppb_var_deprecated_proxy.cc	(revision 142787)
+++ ppapi/proxy/ppb_var_deprecated_proxy.cc	(working copy)
@@ -269,8 +269,10 @@
   PP_Var ret_var = result.Return(dispatcher);
 
   // Register this object as being implemented by the plugin.
-  tracker->PluginImplementedObjectCreated(instance, ret_var,
-                                          ppp_class, ppp_class_data);
+  if (ret_var.type == PP_VARTYPE_OBJECT) {
+    tracker->PluginImplementedObjectCreated(instance, ret_var,
+                                            ppp_class, ppp_class_data);
+  }
   return ret_var;
 }