Kill NodeListNameCacheMap cache in NodeListsNodeData

Kill NodeListNameCacheMap cache in NodeListsNodeData. These days, all node
lists use an atomic name so this is unused code.

R=eseidel, adamk

Review URL: https://codereview.chromium.org/146973007

git-svn-id: svn://svn.chromium.org/blink/trunk@166831 bbb929c8-8fbe-4397-9dbb-9b2b20218538