DevTools: Fix console.table wrap lines.

The console.table's rows should be nowrap, and they are, but child DOM
of DataGridNodes may override the "white-space" CSS.
Force nowrap property recursively on the DataGridNode content.

BUG=306915
R=pfeldman,caseq

Review URL: https://codereview.chromium.org/26156003

git-svn-id: svn://svn.chromium.org/blink/trunk@159888 bbb929c8-8fbe-4397-9dbb-9b2b20218538