DevTools: Drastically simplify suggest box and make it dramatically faster by adding some flex-based css layout.

R=pfeldman, lushnikov, apavlov
NOTRY=true

Review URL: https://codereview.chromium.org/257543003

git-svn-id: svn://svn.chromium.org/blink/trunk@172612 bbb929c8-8fbe-4397-9dbb-9b2b20218538