Fetch parentNode after toNormalizedRange() call has happened in containsNode()

toNormalizedRange() call can trigger layout, there removing the last
reference to parentNode. We don't need to RefPtr parentNode since later
callers don't modify it.

BUG=242114

Review URL: https://chromiumcodereview.appspot.com/15390003

git-svn-id: svn://svn.chromium.org/blink/trunk@150685 bbb929c8-8fbe-4397-9dbb-9b2b20218538
3 files changed