DevTools: DataGrid: properly refresh detached nodes.

I've found that requests in network panel are not refreshed,
because detached nodes ignore refresh request.

BUG=

Review URL: https://codereview.chromium.org/398263003

git-svn-id: svn://svn.chromium.org/blink/trunk@178369 bbb929c8-8fbe-4397-9dbb-9b2b20218538