Update DevTools CSS for media and text track network resources.
Update DevTools CSS for media and text track network resources.

The CL below added the resource types media (for <audio> and <video>
sources) and texttrack (for tracks used by <video>).
https://codereview.chromium.org/114123005/

The CL was written before the CSS for the resource load timing bars in
the network panel moved away from using images, for better support on
high-DPI displays.
https://codereview.chromium.org/99923009/o

This change updates the CSS for media and texttrack resources to match
the new format.

BUG=329817
TEST=Load http://www.samdutton.com/track/simple.html with DevTools open.

Review URL: https://codereview.chromium.org/233413003

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@171336 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs