Do not mark !needsLayout() assert in RenderTableSection::paint as having security implications.
R=inferno@chromium.org

BUG=

Review URL: https://codereview.chromium.org/197173003

git-svn-id: svn://svn.chromium.org/blink/trunk@169034 bbb929c8-8fbe-4397-9dbb-9b2b20218538