Test cases for bugs 1982, 7988, 8253, and 8285.

These four bugs were all fixed by my "future of CTFE" pull request. Here, I add the test cases to ensure they stay fixed.

http://d.puremagic.com/issues/show_bug.cgi?id=1982
http://d.puremagic.com/issues/show_bug.cgi?id=7988
http://d.puremagic.com/issues/show_bug.cgi?id=8253
http://d.puremagic.com/issues/show_bug.cgi?id=8285