Attached the repro. VisibleSelection::adjustSelectionToAvoidCrossingShadowBoundaries seems wrong. Since there is no last position in <meter>, we cannot take lastPositionInNode(<meter>). Maybe we should use lastPositionInOrAfterNode() instead.
Created attachment 133753 [details] Repro
Created attachment 133755 [details] Patch
Committed r112197: <http://trac.webkit.org/changeset/112197>