TextEditor: Delete also duplicated assist items

~GenericProposalModel() did not delete all original items loaded, but the
original items minus the recognized duplicates.

Change-Id: If34f805f8f86391be6e7590e943c1c5adac14869
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: David Schulz <david.schulz@theqtcompany.com>

src/plugins/texteditor/codeassist/genericproposalmodel.cpp

@@ -179,6 +179,7 @@ void GenericProposalModel::removeDuplicates()
         const AssistProposalItemInterface *item = *it;
         if (unique.contains(item->text())
                 && unique.value(item->text()) == item->hash()) {
+            delete *it;
             it = m_originalItems.erase(it);
         } else {
             unique.insert(item->text(), item->hash());