Summary: SelectionController should not extend the selection when allowsMultipleSelection is false. Note: It isn't possible to circumvent the `allowsMultipleSelection` flag using the UI (by shift/command-clicking). This change will prevent circumventing the flag by setting `extendSelection = true` when calling `SelectionController.prototype.selectItem`.
<rdar://problem/46473624>
Created attachment 356567 [details] Patch
Comment on attachment 356567 [details] Patch r=me
Comment on attachment 356567 [details] Patch Clearing flags on attachment: 356567 Committed r238914: <https://trac.webkit.org/changeset/238914>
All reviewed patches have been landed. Closing bug.