Handle the case where the v8 scriptable object has a property defined with value undefined.

ppapi/tests/blink_deprecated_test_plugin.cc

Index: ppapi/tests/blink_deprecated_test_plugin.cc
diff --git a/ppapi/tests/blink_deprecated_test_plugin.cc b/ppapi/tests/blink_deprecated_test_plugin.cc
index e179bc7800555b84ae4f1b8258e1efccbc7af3a6..229e8c23f12776d4508627ce1f412116e0b07e94 100644
--- a/ppapi/tests/blink_deprecated_test_plugin.cc
+++ b/ppapi/tests/blink_deprecated_test_plugin.cc
@@ -137,6 +137,9 @@ class InstanceSO : public ScriptableBase {
     properties_.insert(std::make_pair(
         "testObject", base::Bind(&InstanceSO::TestObjectAccessor,
                                  base::Unretained(this))));
+    properties_.insert(std::make_pair(
+        "testGetUndefined", base::Bind(&InstanceSO::TestGetUndefinedAccessor,
+                                       base::Unretained(this))));
   }
   ~InstanceSO() override {}
 
@@ -190,6 +193,12 @@ class InstanceSO : public ScriptableBase {
     *var = test_object_;
   }
 
+  void TestGetUndefinedAccessor(bool set, pp::Var* var) {
+    if (set)
+      return;
+    *var = pp::Var();
+  }
+
   pp::VarPrivate test_object_;
 };