Fix for Dirac off-diagonal Jacobian entries.

This is a quick fix for three tests that crash in debug mode so that we
can keep the build page running, I am working on trying to track down
the root cause of the issue.

Refs #668.
Merge pull request #3442 from jwpeterson/fixup_dirac_offdiag

Fix for Dirac off-diagonal Jacobian entries.
Merge commit 'd9509d5de73852bee477f46684c2e3f8e6d3547c'