Fix indentation in namespace in two files: SharedWorkerGlobalScope.h, WorkerMessagingProxy.h

NOTRY=true

Review URL: https://codereview.chromium.org/407493005

git-svn-id: svn://svn.chromium.org/blink/trunk@178450 bbb929c8-8fbe-4397-9dbb-9b2b20218538