Hide last updated data until date is populated.

This fixes an issue where "last updated" data would be displayed before date
was populated, showing some weird data. I tried to use "template if" to
restrict when this would be painted, but couldn't get that to work, so I
resorted to using styling instead.

NOTRY=true
BUG=402661

Review URL: https://codereview.chromium.org/466783002

git-svn-id: svn://svn.chromium.org/blink/trunk@180100 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Convert net.js & net_unittests.js to html files

Moving them to lib, wrapping them in script tags, and converting
the test to Mocha.

BUG=400388
NOTRY=true

Review URL: https://codereview.chromium.org/464003002

git-svn-id: svn://svn.chromium.org/blink/trunk@180101 bbb929c8-8fbe-4397-9dbb-9b2b20218538