Fixed <rdar://problem/3880561> Default string value of ObjC object in JS...

    Fixed <rdar://problem/3880561> Default string value of ObjC object in JS should be [obj description].

        Reviewed by Hyatt.

        * bindings/objc/objc_instance.mm:
        (ObjcInstance::stringValue):
        * bindings/objc/objc_utility.h:
        * bindings/objc/objc_utility.mm:
        (KJS::Bindings::convertNSStringToString):
        (KJS::Bindings::convertObjcValueToValue):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@8019 268f45cc-cd09-0410-ab3c-d52691b4dbfc