CharacterData::appendData and replaceData don't need to pass AttachBehavior

Nothing ever passes DeprecatedAttachNow into these methods so we don't need
to have the arguments to them.

Review URL: https://chromiumcodereview.appspot.com/23658016

git-svn-id: svn://svn.chromium.org/blink/trunk@157232 bbb929c8-8fbe-4397-9dbb-9b2b20218538