Add a TurboFan skeleton for StringAddStub.

src/runtime.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This files contains runtime support implemented in JavaScript.
 
 // CAUTION: Some of the functions specified in this file are called
 // directly from compiled code. These are the functions with names in
 // ALL CAPS. The compiled code passes the first argument in 'this'.
 
@@ skipping 47 matching lines @@
 var APPLY_PREPARE;
 var REFLECT_APPLY_PREPARE;
 var REFLECT_CONSTRUCT_PREPARE;
 var STACK_OVERFLOW;
 var TO_OBJECT;
 var TO_NUMBER;
 var TO_STRING;
 var TO_NAME;
 
 var StringLengthTF_STUB;
+var StringAddTF_STUB;
 var MathFloor_STUB;
 
 var $defaultNumber;
 var $defaultString;
 var $NaN;
 var $nonNumberToNumber;
 var $nonStringToString;
 var $sameValue;
 var $sameValueZero;
 var $toBoolean;
@@ skipping 687 matching lines @@
    - - -   J a v a S c r i p t   S t u b s   - - -
    -----------------------------------------------
 */
 
 StringLengthTF_STUB = function StringLengthTF_STUB(receiver, name, i, v) {
   // i and v are dummy parameters mandated by the InterfaceDescriptor,
   // (LoadWithVectorDescriptor).
   return %_StringGetLength(%_JSValueGetValue(receiver));
 }
 
+StringAddTF_STUB = function StringAddTF_STUB(left, right) {
+  return %StringAdd(left, right);
+}
+
 MathFloor_STUB = function MathFloor_STUB(f, i, v) {
   // |f| is calling function's JSFunction
   // |i| is TypeFeedbackVector slot # of callee's CallIC for Math.floor call
   // |v| is the value to floor
   var r = %_MathFloor(+v);
   if (%_IsMinusZero(r)) {
     // Collect type feedback when the result of the floor is -0. This is
     // accomplished by storing a sentinel in the second, "extra"
     // TypeFeedbackVector slot corresponding to the Math.floor CallIC call in
     // the caller's TypeVector.
@@ skipping 253 matching lines @@
 $toLength = ToLength;
 $toName = ToName;
 $toNumber = ToNumber;
 $toObject = ToObject;
 $toPositiveInteger = ToPositiveInteger;
 $toPrimitive = ToPrimitive;
 $toString = ToString;
 $toUint32 = ToUint32;
 
 })