[PATCH v4 1/2] msxml3: Null check newChild in DOMDocument insertBefore.

[Jefferson Carpenter]

Thanks for bearing with me.

Regarding commit messages I was thinking DOMDocument is the name of a 
clsid, so that's the name of the object that should be mentioned. 
Element doesn't seem to be associated with a clsid, so I just said 
'domelem'.  Let me know if you would have a different opinion on that.