Move painting code from RenderReplica to ReplicaPainter.

Just a simple code move.

BUG=412088

Review URL: https://codereview.chromium.org/602973005

git-svn-id: svn://svn.chromium.org/blink/trunk@182712 bbb929c8-8fbe-4397-9dbb-9b2b20218538