Devtools: DataGrid: do not render hidden columns.

Previous implementation used display:none to hide columns.
This caused UI glitches, tremble on resize and performance issues.

In new implementation hidden columns are not rendered at all.

BUG=372246

Review URL: https://codereview.chromium.org/297893003

git-svn-id: svn://svn.chromium.org/blink/trunk@175273 bbb929c8-8fbe-4397-9dbb-9b2b20218538