Reviewed by Maciej.

    Reviewed by Maciej.

        - Fixed <rdar://problem/4334445> installer crashed on my
          dual g4 450Mhz after clicking language

        - Reversed backwards NULL check.
        - Inserted guards against NULL fJSUserObject data member.
        - Cleaned up some style.

        * JSUtils.cpp:
        (KJSValueToCFTypeInternal):
        * UserObjectImp.cpp:
        (UserObjectImp::~UserObjectImp):
        (UserObjectImp::callAsFunction):
        (UserObjectImp::userObjectGetter):
        (UserObjectImp::getOwnPropertySlot):
        (UserObjectImp::put):
        (UserObjectImp::mark):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@12212 268f45cc-cd09-0410-ab3c-d52691b4dbfc