...since it does not make sense for TextEditor::QuickFix and
TextEditor::FollowSymbol.

Regarding the bug:
- The bug was exposed by having "Active completion" set to *not*
  "Manual" in Options > Text Editor > Completion.
- After choosing one item from the overrides list the cursor was
  positioned just right before the beginning of a function name, which
  is a valid activation sequence (see CodeAssistantPrivate::process()))
  As a consequence, a new proposal was requested.

Task-number: QTCREATORBUG-10345
Change-Id: Ib0d10192863fb33c0958a9afbf76ca8e7de772f8
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>