DevTools: [WebSQL] fix websql console to render properly

The elements of websql console use a vertical flex container and thus
overlay each other to fit into screen.

BUG=409415
R=vsevik

Review URL: https://codereview.chromium.org/541803002

git-svn-id: svn://svn.chromium.org/blink/trunk@181408 bbb929c8-8fbe-4397-9dbb-9b2b20218538