Fix wrong unsplit icons when splitting without open documents

When doing splits while no document is open, the wrong unsplit icons
where set on the individual editor views (the ones next to the split
menu button and the close editor button).
This also happened when restoring sessions with splits.

Task-number: QTCREATORBUG-9121
Change-Id: I793670518eddee3e57fef5a4ac4a266edb450b14
Reviewed-by: David Schulz <david.schulz@digia.com>

src/plugins/coreplugin/editormanager/editorview.cpp

@@ -601,8 +601,8 @@ void SplitterOrView::split(Qt::Orientation orientation)
             m_splitter->addWidget((otherView = new SplitterOrView()));
         }
     } else {
-        m_splitter->addWidget((otherView = new SplitterOrView()));
         m_splitter->addWidget((view = new SplitterOrView()));
+        m_splitter->addWidget((otherView = new SplitterOrView()));
     }
 
     m_layout->setCurrentWidget(m_splitter);