Fix VariableToolTip auto resizing.
The VariableToolTip is supposed to resize vertically as much as can fit
in the window whenever the content changes. It was not working because
the m_itemHeight was 0 which was because the QTreeView::indexRowSizeHint
was called with index from m_model instead of m_proxy.
Same for the initial selection below.
Debug some program, stop execution and hover over some variable. Expand
some subitems - the tooltip should be resizing.
Reviewers: KDevelop, kfunk
Reviewed By: KDevelop, kfunk
Subscribers: kfunk, kdevelop-devel
Differential Revision: https://phabricator.kde.org/D14879