Fix crash in QObjectWrapper
Fix crash in QObjectWrapper

This can happen during QObject destruction, when
QObjectPrivate::deleteChildren() itself sets entries
in the children list to zero when deleting. These
zeros cause crash in markChildQObjectsRecursively().

Task-number: QTBUG-38635
Change-Id: I29ad9e793b78ca4e8d73fbb125f46db1b8292f20
Reviewed-by: Alan Alpert <da25f2afbbb946022229108d81aeba0c6b35c5c3@blackberry.com>

qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative