Reviewed by Geoff.

        - https://bugs.webkit.org/show_bug.cgi?id=19721
          speed up JavaScriptCore by not wrapping strings in objects just
          to call functions on them

        - optimize UString append and the replace function a bit

        SunSpider says 1.8% faster.

        * JavaScriptCore.exp: Updated.

        * VM/JSPropertyNameIterator.cpp: Added include of JSString.h, now needed
        because jsString returns a JSString*.

        * VM/Machine.cpp:
        (KJS::Machine::privateExecute): Removed the toObject call from native
        function calls. Also removed code to put the this value into a register.

        * kjs/BooleanObject.cpp:
        (KJS::booleanProtoFuncToString): Rewrite to handle false and true
        separately.

        * kjs/FunctionPrototype.cpp:
        (KJS::constructFunction): Use single-character append rather than building
        a string for each character.
        * kjs/JSFunction.cpp:
        (KJS::globalFuncUnescape): Ditto.

        * kjs/JSImmediate.cpp:
        (KJS::JSImmediate::prototype): Added. Gets the appropriate prototype for
        use with an immediate value. To be used instead of toObject when doing a
        get on an immediate value.
        * kjs/JSImmediate.h: Added prototype.

        * kjs/JSObject.cpp:
        (KJS::JSObject::toString): Tweaked formatting.

        * kjs/JSObject.h:
        (KJS::JSValue::get): Use prototype instead of toObject to avoid creating
        an object wrapper just to search for properties. This also saves an
        unnecessary hash table lookup since the object wrappers themselves don't
        have any properties.

        * kjs/JSString.h: Added toThisString and toThisJSString.

        * kjs/JSValue.cpp:
        (KJS::JSCell::toThisString): Added.
        (KJS::JSCell::toThisJSString): Added.
        (KJS::JSCell::getJSNumber): Added.
        (KJS::jsString): Changed return type to JSString*.
        (KJS::jsOwnedString): Ditto.

        * kjs/JSValue.h:
        (KJS::JSValue::toThisString): Added.
        (KJS::JSValue::toThisJSString): Added.
        (KJS::JSValue::getJSNumber): Added.

        * kjs/NumberObject.cpp:
        (KJS::NumberObject::getJSNumber): Added.
        (KJS::integer_part_noexp): Append C string directly rather than first
        turning it into a UString.
        (KJS::numberProtoFuncToString): Use getJSNumber to check if the value
        is a number rather than isObject(&NumberObject::info). This works for
        immediate numbers, number cells, and NumberObject instances.
        (KJS::numberProtoFuncToLocaleString): Ditto.
        (KJS::numberProtoFuncValueOf): Ditto.
        (KJS::numberProtoFuncToFixed): Ditto.
        (KJS::numberProtoFuncToExponential): Ditto.
        (KJS::numberProtoFuncToPrecision): Ditto.
        * kjs/NumberObject.h: Added getJSNumber.

        * kjs/PropertySlot.cpp: Tweaked comment.

        * kjs/internal.cpp:
        (KJS::JSString::toThisString): Added.
        (KJS::JSString::toThisJSString): Added.
        (KJS::JSString::getOwnPropertySlot): Changed code that searches the
        prototype chain to start with the string prototype and not create a
        string object.
        (KJS::JSNumberCell::toThisString): Added.
        (KJS::JSNumberCell::getJSNumber): Added.

        * kjs/lookup.cpp:
        (KJS::staticFunctionGetter): Moved here, because there's no point in
        having a function that's only used for a function pointer be inline.
        (KJS::setUpStaticFunctionSlot): New function for getStaticFunctionSlot.

        * kjs/lookup.h:
        (KJS::staticValueGetter): Don't mark this inline. It doesn't make sense
        to have a function that's only used for a function pointer be inline.
        (KJS::getStaticFunctionSlot): Changed to get properties from the parent
        first before doing any handling of functions. This is the fastest way
        to return the function once the initial setup is done.

        * kjs/string_object.cpp:
        (KJS::StringObject::getPropertyNames): Call value() instead of getString(),
        avoiding an unnecessary virtual function call (the call to the type()
        function in the implementation of the isString() function).
        (KJS::StringObject::toString): Added.
        (KJS::StringObject::toThisString): Added.
        (KJS::StringObject::toThisJSString): Added.
        (KJS::substituteBackreferences): Rewrote to use a appending algorithm
        instead of a the old one that tried to replace in place.
        (KJS::stringProtoFuncReplace): Merged this function and the replace function.
        Replaced the hand-rolled dynamic arrays for source ranges and replacements
        with Vector.
        (KJS::stringProtoFuncToString): Handle JSString as well as StringObject.
        Removed the separate valueOf implementation, since it can just share this.
        (KJS::stringProtoFuncCharAt): Use toThisString, which handles JSString as
        well as StringObject, and is slightly more efficient than the old code too.
        (KJS::stringProtoFuncCharCodeAt): Ditto.
        (KJS::stringProtoFuncConcat): Ditto.
        (KJS::stringProtoFuncIndexOf): Ditto.
        (KJS::stringProtoFuncLastIndexOf): Ditto.
        (KJS::stringProtoFuncMatch): Ditto.
        (KJS::stringProtoFuncSearch): Ditto.
        (KJS::stringProtoFuncSlice): Ditto.
        (KJS::stringProtoFuncSplit): Ditto.
        (KJS::stringProtoFuncSubstr): Ditto.
        (KJS::stringProtoFuncSubstring): Ditto.
        (KJS::stringProtoFuncToLowerCase): Use toThisJSString.
        (KJS::stringProtoFuncToUpperCase): Ditto.
        (KJS::stringProtoFuncToLocaleLowerCase): Ditto.
        (KJS::stringProtoFuncToLocaleUpperCase): Ditto.
        (KJS::stringProtoFuncLocaleCompare): Ditto.
        (KJS::stringProtoFuncBig): Use toThisString.
        (KJS::stringProtoFuncSmall): Ditto.
        (KJS::stringProtoFuncBlink): Ditto.
        (KJS::stringProtoFuncBold): Ditto.
        (KJS::stringProtoFuncFixed): Ditto.
        (KJS::stringProtoFuncItalics): Ditto.
        (KJS::stringProtoFuncStrike): Ditto.
        (KJS::stringProtoFuncSub): Ditto.
        (KJS::stringProtoFuncSup): Ditto.
        (KJS::stringProtoFuncFontcolor): Ditto.
        (KJS::stringProtoFuncFontsize): Ditto.
        (KJS::stringProtoFuncAnchor): Ditto.
        (KJS::stringProtoFuncLink): Ditto.

        * kjs/string_object.h: Added toString, toThisString, and toThisJSString.

        * kjs/ustring.cpp:
        (KJS::UString::append): Added a version that takes a character pointer and
        size, so we don't have to create a UString just to append to another UString.
        * kjs/ustring.h:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@34821 268f45cc-cd09-0410-ab3c-d52691b4dbfc