Amends 32b586864e, which added an override
of QStandardItemModel::roleNames(). It's good for it to have its own
QHash so that roles can be added, and because
QStandardItemModel::setItemRoleNames() remains un-deprecated; but before
that change, they were the roles that QAbstractItemModel had initialized
from QAbstractItemModelPrivate::defaultRoleNames(). In particular, we
need "display" to map to Qt::DisplayRole by default; several tests in
qtdeclarative depend on that.
Change-Id: I58b2d6aa6b6c78b1d618335ddc4ecb834af57274
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>