DevTools: Remove remaining usage of resourceView.css deleted in r182834

TBR=pfeldman
BUG=419303
NOTRY=true

Review URL: https://codereview.chromium.org/622533002

git-svn-id: svn://svn.chromium.org/blink/trunk@183048 bbb929c8-8fbe-4397-9dbb-9b2b20218538