Get rid of unused member function rootEditableElement() in PositionAlgorithm<Strategy> template class
Get rid of unused member function rootEditableElement() in PositionAlgorithm<Strategy> template class

This patch gets rid of unused member function |rootEditableElement()| in
|PositionAlgorithm<Strategy>| template class to simplify source code for
improving code health.

BUG=518738
TEST=n/a; no behavior changes

Review URL: https://codereview.chromium.org/1303673002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@200805 bbb929c8-8fbe-4397-9dbb-9b2b20218538

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk