Range should not use confusingAndOftenMisusedAttached()

Range is really checking inActiveDocument() and is confused.

Review URL: https://codereview.chromium.org/49913002

git-svn-id: svn://svn.chromium.org/blink/trunk@160768 bbb929c8-8fbe-4397-9dbb-9b2b20218538