Clean up ViewportDescription.

Get rid of unused 'includes' and forward declarations.

BUG=None

Review URL: https://codereview.chromium.org/39823002

git-svn-id: svn://svn.chromium.org/blink/trunk@160566 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: [Styles] Make individual selectors Ctrl-click navigable, fix effective rule location

The rule raw location is now computed as the location of the first matching selector in the list.

R=pfeldman, vsevik
BUG=266416

Review URL: https://codereview.chromium.org/26554007

git-svn-id: svn://svn.chromium.org/blink/trunk@160567 bbb929c8-8fbe-4397-9dbb-9b2b20218538