Renamed StartDequeue -> Peek, FinishDequeue -> Remove.

BUG=None
R=bmeurer@chromium.org, loislo@chromium.org

Review URL: https://codereview.chromium.org/23686006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16549 ce2b1a6d-e550-0410-aec6-3dcde31c8c00