The following DRT tests seem to be not working in DRT mode:
fast/frames/sandboxed-iframe-history-denied.html
fast/frames/sandboxed-iframe-navigation-parent.html

The latter, however, seems to work in manual mode.

Affected tests:
WebNodeDrt/fast/frames/sandboxed-iframe-history-denied.html
WebNodeDrt/fast/frames/sandboxed-iframe-navigation-parent.html