DevTools: [CSS] remove StyleId and RuleId types from protocol.json

This patch removes StyleId and RuleId types from protocol.json as
they are not needed any more.

BUG=341506

Review URL: https://codereview.chromium.org/198053011

git-svn-id: svn://svn.chromium.org/blink/trunk@170972 bbb929c8-8fbe-4397-9dbb-9b2b20218538