When script execution resumes all call stack placards are left as listeners of corresponding RawSourceCode.
See WebInspector.DebuggerPresentationModel.prototype.createPlacard and WebInspector.CallStackSidebarPane.prototype.update
Created attachment 112649 [details] Patch
Comment on attachment 112649 [details] Patch Can we get a test for this?
Created attachment 112830 [details] Patch
Committed r98710: <http://trac.webkit.org/changeset/98710>