methods will cause browser to crash"), fix contributed by
jeff.dyer@compilercompany.com, r=drapeau@eng.sun.com. More
bulletproof way of testing if principals passed in are valid (comments
in the code fix explain in more detail).
git-svn-id: svn://10.0.0.236/trunk@54836 18797224-902f-48f8-a5cc-f745e15eee43