Ensure correct state for resources fetched via fetch???Resource.

This CL asserts that resources fetched via the various
'ResourceFetcher::fetch???Resource' methods have a frame-type of 'none'
and sets the request context as appropriate.

BUG=390497

Review URL: https://codereview.chromium.org/390833002

git-svn-id: svn://svn.chromium.org/blink/trunk@178260 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: DataGrid: introduce top filler row.

Currently datagrid have only bottom filler to pad tables to fit container.

Top filler is used by viewport datagrid subclasses.
But adding it make generic datagrid logic simpler.

BUG=

Review URL: https://codereview.chromium.org/384673003

git-svn-id: svn://svn.chromium.org/blink/trunk@178261 bbb929c8-8fbe-4397-9dbb-9b2b20218538