Fix a crash in setInternalClass

Revealed by the ES6 testsuite, ./test/built-ins/Object/freeze/15.2.3.9-2-1.js
and probably others. We cannot unconditionally dereference memberData,
it may not always exist.

ES6 tests test/built-ins/Object/freeze before:
    === Summary ===
     - Ran 92 tests
     - Passed 66 tests (71.7%)
     - Failed 26 tests (28.3%)

after:
    === Summary ===
     - Ran 92 tests
     - Passed 90 tests (97.8%)
     - Failed 2 tests (2.2%)

Change-Id: I22a6c9ca081394ba15edfde09f73769eb3ce47b3
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 14 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
index 89dac33671..83725dbf12 100644
--- a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
+++ b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
@@ -333,6 +333,7 @@ private slots:
     void stringify_qtbug_50592();
     void instanceof_data();
     void instanceof();
+    void freeze_empty_object();
 
 private:
 //    static void propertyVarWeakRefCallback(v8::Persistent<v8::Value> object, void* parameter);
@@ -8183,6 +8184,19 @@ void tst_qqmlecmascript::instanceof()
     }
 }
 
+void tst_qqmlecmascript::freeze_empty_object()
+{
+    // this shouldn't crash
+    QJSEngine engine;
+    QJSValue v = engine.evaluate(QString::fromLatin1(
+            "var obj = {};\n"
+            "Object.freeze(obj);\n"
+    ));
+    QVERIFY(!v.isError());
+    QCOMPARE(v.toBool(), true);
+}
+
+
 QTEST_MAIN(tst_qqmlecmascript)
 
 #include "tst_qqmlecmascript.moc"