The timeline models were suspended for editing but never restored. To
test the correct behavior a test case for the trace view is added.
Change-Id: Ic1803e9d84656eed97795f1f1674e3d56c83f650
Task-number: QTCREATORBUG-18354
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
