[PATCH 4/4] msxml3/tests: Test for methods that break lock with writer domdoc dest.

[Jefferson Carpenter]

I actually don't like 4/4 as much since the 2 helper methods I added 
`begin_writing_to_domdoc` and `check_domdoc_lock_broken` pretty much 
arbitrarily factor out code.  Nevertheless, I would be fine maintaining 
this test, so please let me know what you think.

thanks,
Jefferson