Make DeleteSelectionCommand not to use Position::deprecatedEditingOffset()
Make DeleteSelectionCommand not to use Position::deprecatedEditingOffset()

This patch replaces |Position::deprecatedEditingOffset()| call in
|DeleteSelectionCommand| class by |Position::computeEditingOffset()|, since it
is used for computing offset for upstream/downstream positions which can not be
middle of editing ignore content, for improving code health.

This patch is a preparation of getting rid of legacy editing position.

BUG=513114
TEST=n/a; no behavior changes

Review URL: https://codereview.chromium.org/1265123002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@199886 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk