VCS: Make submit editor closing independent from current editor

The VCS plugins keep a reference to the submit editor, so it can
explicitly be closed, instead of relying on the correct currentEditor in
the editor manager.

Change-Id: I14aab63447f790f2065a8d8dc6b50aeacbd1e941
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/mercurial/mercurialplugin.cpp

@@ -596,7 +596,7 @@ void MercurialPlugin::commitFromEditor()
 {
     // Close the submit editor
     m_submitActionTriggered = true;
-    Core::EditorManager::closeEditor();
+    Core::EditorManager::closeEditor(submitEditor());
 }
 
 bool MercurialPlugin::submitEditorAboutToClose()