DevTools: [Documentation] Improve documentation rendering

The patch migrates documentation rendering to the look and feel
of the chrome developers documentation. It also adds support for
rendering of tables.

BUG=415492

Review URL: https://codereview.chromium.org/578333002

git-svn-id: svn://svn.chromium.org/blink/trunk@182315 bbb929c8-8fbe-4397-9dbb-9b2b20218538