When removing multiple lines in the tree view of the profiler (focused on a function) it will re-add previously removed lines (from other branches of the tree) randomly back. Quite annoying as it makes the remove feature virtually useless. :/
Closing as invalid, as this bug pertains to the old inspector UI and/or its tests. Please file a new bug (https://www.webkit.org/new-inspector-bug) if the bug/feature/issue is still relevant to WebKit trunk.