Move markerlists to Oilpan heap and remove finalizer from DocumentMarkerController

R=ager@chromium.org, haraken@chromium.org, sigbjornf@opera.com
BUG=

Review URL: https://codereview.chromium.org/289323003

git-svn-id: svn://svn.chromium.org/blink/trunk@174362 bbb929c8-8fbe-4397-9dbb-9b2b20218538