Remove usages of temporary Range objects that end up registered on the
Document for no reason.

This is important for Oilpan because the Ranges do not die until the
next GC. This gives a 10% improvement on DOM/textarea-edit in the
oilpan build.

R=yosin@chromium.org
BUG=388681

Review URL: https://codereview.chromium.org/565613002

git-svn-id: svn://svn.chromium.org/blink/trunk@181889 bbb929c8-8fbe-4397-9dbb-9b2b20218538