ActionManager: Require a valid context for shortcuts

All callers provide one, and the fall-back construction from 0
has not been appropriate for a while.

Change-Id: I8bc5d094b70aac251fff1a7d34f1fad876cbdee2
Reviewed-by: Daniel Teske <daniel.teske@digia.com>

src/plugins/coreplugin/actionmanager/actionmanager.cpp

@@ -258,6 +258,7 @@ Command *ActionManager::registerAction(QAction *action, const Id &id, const Cont
 */
 Command *ActionManager::registerShortcut(QShortcut *shortcut, const Id &id, const Context &context, bool scriptable)
 {
+    QTC_CHECK(!context.isEmpty());
     Shortcut *sc = 0;
     if (CommandPrivate *c = m_instance->d->m_idCmdMap.value(id, 0)) {
         sc = qobject_cast<Shortcut *>(c);
@@ -282,10 +283,6 @@ Command *ActionManager::registerShortcut(QShortcut *shortcut, const Id &id, cons
     shortcut->setParent(ICore::mainWindow());
     sc->setShortcut(shortcut);
     sc->setScriptable(scriptable);
-
-    if (context.isEmpty())
-        sc->setContext(Context(0));
-    else
     sc->setContext(context);
 
     emit m_instance->commandListChanged();