Don't dereference a null animationTemplate

If the SpringAnimation gets used inside a Transition, the
animationTemplate might get cleared, but updateCurrentTime()
still gets called on the SpringAnimation after that.

Task-number: QTBUG-34539
Change-Id: I1f27fdbfc594e6ff9a4343e45f7f4001964bb012
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>

src/quick/util/qquickspringanimation.cpp

@@ -308,7 +308,8 @@ void QSpringAnimation::updateCurrentTime(int time)
                                        QQmlPropertyPrivate::DontRemoveBinding);
 
     if (stopped && old_to == to) { // do not stop if we got restarted
-        stopTime = animationTemplate->elapsed.elapsed();
+        if (animationTemplate)
+            stopTime = animationTemplate->elapsed.elapsed();
         stop();
     }
 }

tests/auto/quick/qquickspringanimation/data/inTransition.qml

@@ -0,0 +1,22 @@
+import QtQuick 2.0
+
+Rectangle {
+    width: 250
+    height: 250
+
+    ListView {
+        anchors.fill: parent
+        model: ListModel {
+            ListElement { text: "A" }
+            ListElement { text: "B" }
+        }
+
+        populate: Transition {
+            SpringAnimation { properties: "x"; from: 0; to: 100; spring: 4; damping: 0.3 }
+        }
+
+        delegate: Text {
+            text: "Test"
+        }
+    }
+}

tests/auto/quick/qquickspringanimation/tst_qquickspringanimation.cpp

@@ -41,6 +41,7 @@
 #include <qtest.h>
 #include <QtQml/qqmlengine.h>
 #include <QtQml/qqmlcomponent.h>
+#include <QtQuick/qquickview.h>
 #include <private/qquickspringanimation_p.h>
 #include <private/qqmlvaluetype_p.h>
 #include "../../shared/util.h"
@@ -55,6 +56,7 @@ private slots:
     void defaultValues();
     void values();
     void disabled();
+    void inTransition();
 
 private:
     QQmlEngine engine;
@@ -128,6 +130,14 @@ void tst_qquickspringanimation::disabled()
     delete obj;
 }
 
+void tst_qquickspringanimation::inTransition()
+{
+    QQuickView view(testFileUrl("inTransition.qml"));
+    view.show();
+    // this used to crash after ~1 sec, once the spring animation was done
+    QTest::qWait(2000);
+}
+
 QTEST_MAIN(tst_qquickspringanimation)
 
 #include "tst_qquickspringanimation.moc"