DevTools: DataGrid: corner td should also have regular td style.
DevTools: DataGrid: corner td should also have regular td style.

BUG=

Review URL: https://codereview.chromium.org/463043002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@180156 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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