Patch for http://bugs.webkit.org/show_bug.cgi?id=13855
        Port patch 666176 to JavaScriptCore

        - Renamed JSValue::downcast() to JSValue::asCell() which makes the
        function meaning cleaner. It's modeled after Harri Porten change in 
        KDE trunk.

        * kjs/collector.cpp:
        (KJS::Collector::protect):
        (KJS::Collector::unprotect):
        (KJS::Collector::collectOnMainThreadOnly):
        * kjs/object.h:
        (KJS::JSValue::isObject):
        * kjs/string_object.cpp:
        (KJS::StringProtoFunc::callAsFunction):
        * kjs/value.h:
        (KJS::JSValue::asCell):
        (KJS::JSValue::isNumber):
        (KJS::JSValue::isString):
        (KJS::JSValue::isObject):
        (KJS::JSValue::getNumber):
        (KJS::JSValue::getString):
        (KJS::JSValue::getObject):
        (KJS::JSValue::getUInt32):
        (KJS::JSValue::mark):
        (KJS::JSValue::marked):
        (KJS::JSValue::type):
        (KJS::JSValue::toPrimitive):
        (KJS::JSValue::toBoolean):
        (KJS::JSValue::toNumber):
        (KJS::JSValue::toString):
        (KJS::JSValue::toObject):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@21736 268f45cc-cd09-0410-ab3c-d52691b4dbfc