Clean results of last Qml profiling do not clean up categories

Steps to reproduce:

• open/create Qt Quick 2 Application, profile this app to get some events
• when done check Timeline and Events contain some valid information
• hit 'Clean' tool button (when being on the Events or JavaScript tab)
• get back to the Timeline - Timeline is cleaned but categories still having the subcategories of the last profiling

Expected behavior:

• hitting 'Clean' on one of the tabs should always clean all results (cleaning subcategories is done fine when hitting 'Clean' on the Timeline tab)