Cleanup namespace usage in modules/.

BUG=None
TEST=blink_tests
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/454353002

git-svn-id: svn://svn.chromium.org/blink/trunk@179981 bbb929c8-8fbe-4397-9dbb-9b2b20218538