DevTools: console.table attached inside a collapsed console group is not resizeable.

A DataGrid being attached to a hidden parent (e.g. collapsed console group) can not
initialize column widths right away and just skips it. And it will never do so
unless explicitly asked. Thus the problem happens when the parent becomes visible.

To overcome this we call wasShown() for console messages and groups recursively.

BUG=306120
R=pfeldman,vsevik,eustas@chromium.org

Review URL: https://codereview.chromium.org/28923003

git-svn-id: svn://svn.chromium.org/blink/trunk@160457 bbb929c8-8fbe-4397-9dbb-9b2b20218538