See attached screenshot. For some reason, you can select individual resources in the list. So, I tried to select several at once by shift-clicking (on Mac). But what I got was a super weird mix of list item plus text selection. This may be a general problem with Web Inspector list implementation - I didn't check that.
Created attachment 92015 [details] screenshot
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.