Use Blink-style method casing for EndOfScopeTask::run()

I guess we're all so used to looking at Chromium's
base::Callback::Run() that no-one noticed. Oops!

R=haraken@chromium.org

Review URL: https://codereview.chromium.org/724953002

git-svn-id: svn://svn.chromium.org/blink/trunk@185330 bbb929c8-8fbe-4397-9dbb-9b2b20218538