Auto-rebaseline for r170960

http://src.chromium.org/viewvc/blink?view=revision&revision=170960

BUG=354305
TBR=fs@opera.com

Review URL: https://codereview.chromium.org/232103004

git-svn-id: svn://svn.chromium.org/blink/trunk@171201 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Make HTMLCollection / NodeList backward traversal consistent with forward one

This makes the code clearer and more consistent. There is no reason to handle
backward traversal differently from forward traversal.

This CL also updates to make ElementTraversal::lastWithin() actually return
the last descendant of Element type, and not the last child Element. This is
not equivalent. ElementTraversal::lastChild() should be used instead to get
the last child Element. This results in the removal of
LiveNodeListBase::lastDescendant() method.

R=esprehn@chromium.org, adamk@chromium.org

Review URL: https://codereview.chromium.org/229213002

git-svn-id: svn://svn.chromium.org/blink/trunk@171202 bbb929c8-8fbe-4397-9dbb-9b2b20218538