Fix "Type error" when creating a TextField with focus: true
Added simple example "line-edit with clear button" written by Laurent,
to demonstrate the issue.
This leads to a "Type error" warning in MobileTextActionsToolBar.qml
or more precisely with my qtdeclarative fix
MobileTextActionsToolBar.qml:47: TypeError: Cannot read property 'height' of null
which means controlRoot.Window.contentItem is null.
I'm not 100% confident with this fix, because it feels like stuff
won't be updated when contentItem is non-null later... But I can't
see a bug, I guess it would only happen on mobile?
Test Plan: qmlscene tests/LineEditWithClearButton.qml
Reviewers: mart, davidedmundson, apol, broulik
Reviewed By: apol
Differential Revision: https://phabricator.kde.org/D21517