Web Runner results leak between invocations

Take a story that passes:

Confirm it passes. Change it so that it does not pass. In this case, change 5.0 to 888. The re-run.

Note that it fails as expected.

Change it back to the 'passing' grammar again, and re-run.

Note that it apparently fails. Any repeated clicking of the 'run' button shows the failed results again and again