Fix empty arrays in QML 1

Commit bb0239e added a regression, where empty arrays would produce errors
in QML 1.

Task-number: QTBUG-43656
Change-Id: I6d416b2387a1dfd3588c000368fc1223d08399bd
Reviewed-by: Simon Hausmann <[email protected]>

Author: Robert Griebl

src/declarative/qml/qdeclarativeengine.cpp

@@ -2145,6 +2145,8 @@ QVariant QDeclarativeEnginePrivate::scriptValueToVariant(const QScriptValue &val
 
     if (val.isArray()) {
         int length = val.property(QLatin1String("length")).toInt32();
+        if (!length)
+            containsQObjects = true;
         for (int ii = 0; ii < length; ++ii) {
             if (val.property(ii).isQObject()) {
                 containsQObjects = true;

tests/auto/declarative/qdeclarativeecmascript/tst_qdeclarativeecmascript.cpp

@@ -457,6 +457,12 @@ void tst_qdeclarativeecmascript::arrayExpressions()
     QCOMPARE(list2.at(1), QVariant(2));
     QCOMPARE(list2.at(2), QVariant(QString("foo")));
     QCOMPARE(list2.at(3), QVariant(QString("bar")));
+
+    MyExpression expr3(&context, "[]");
+    result = expr3.evaluate();
+    QCOMPARE(result.userType(), qMetaTypeId<QList<QObject *> >());
+    QList<QObject *> list3 = qvariant_cast<QList<QObject *> >(result);
+    QCOMPARE(list3.count(), 0);
 }
 
 // Tests that modifying a context property will reevaluate expressions