This happens because the inspector protocol will send the remove event before the element is actually going to be removed and the CSS Regions API will not be able to find the nodeId for the removed node.
<rdar://problem/15363312>
Created attachment 216248 [details] Patch V1
Comment on attachment 216248 [details] Patch V1 View in context: https://bugs.webkit.org/attachment.cgi?id=216248&action=review > Source/WebInspectorUI/UserInterface/ContentFlowTreeContentView.js:186 > - this._nodesMap.remove(event.data.node.id); > + this._nodesMap.delete(event.data.node.id); Opps, good catch. > Source/WebInspectorUI/UserInterface/DOMTreeManager.js:43 > + this._contentNodesToFlowsMap = new Map(); No () is our style.
Created attachment 216308 [details] Patch for landing
Comment on attachment 216308 [details] Patch for landing Rejecting attachment 216308 [details] from commit-queue. Failed to run "['/Volumes/Data/EWS/WebKit/Tools/Scripts/webkit-patch', '--status-host=webkit-queues.appspot.com', '--bot-id=webkit-cq-02', 'validate-changelog', '--check-oops', '--non-interactive', 216308, '--port=mac']" exit_code: 1 cwd: /Volumes/Data/EWS/WebKit ChangeLog entry in LayoutTests/ChangeLog contains OOPS!. Full output: http://webkit-queues.appspot.com/results/22638240
Comment on attachment 216308 [details] Patch for landing Clearing flags on attachment: 216308 Committed r158854: <http://trac.webkit.org/changeset/158854>
All reviewed patches have been landed. Closing bug.