[turbofan] First step towards sanitizing for-in and making it optimizable.

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 31 matching lines @@
 var BIT_XOR_STRONG;
 var SHL;
 var SHL_STRONG;
 var SAR;
 var SAR_STRONG;
 var SHR;
 var SHR_STRONG;
 var DELETE;
 var IN;
 var INSTANCE_OF;
-var FILTER_KEY;
 var CALL_NON_FUNCTION;
 var CALL_NON_FUNCTION_AS_CONSTRUCTOR;
 var CALL_FUNCTION_PROXY;
 var CALL_FUNCTION_PROXY_AS_CONSTRUCTOR;
 var CONCAT_ITERABLE_TO_ARRAY;
 var APPLY_PREPARE;
 var REFLECT_APPLY_PREPARE;
 var REFLECT_CONSTRUCT_PREPARE;
 var STACK_OVERFLOW;
 var TO_OBJECT;
@@ skipping 491 matching lines @@
   var O = F.prototype;
   if (!IS_SPEC_OBJECT(O)) {
     throw %MakeTypeError(kInstanceofNonobjectProto, O);
   }
 
   // Return whether or not O is in the prototype chain of V.
   return %IsInPrototypeChain(O, V) ? 0 : 1;
 }
 
 
-// Filter a given key against an object by checking if the object
-// has a property with the given key; return the key as a string if
-// it has. Otherwise returns 0 (smi). Used in for-in statements.
-FILTER_KEY = function FILTER_KEY(key) {
-  var string = %$toName(key);
-  if (%HasProperty(this, string)) return string;
-  return 0;
-}
-
-
 CALL_NON_FUNCTION = function CALL_NON_FUNCTION() {
   var delegate = %GetFunctionDelegate(this);
   if (!IS_FUNCTION(delegate)) {
     var callsite = %RenderCallSite();
     if (callsite == "") callsite = typeof this;
     throw %MakeTypeError(kCalledNonCallable, callsite);
   }
   return %Apply(delegate, this, arguments, 0, %_ArgumentsLength());
 }
 
@@ skipping 468 matching lines @@
 $toLength = ToLength;
 $toName = ToName;
 $toNumber = ToNumber;
 $toObject = ToObject;
 $toPositiveInteger = ToPositiveInteger;
 $toPrimitive = ToPrimitive;
 $toString = ToString;
 $toUint32 = ToUint32;
 
 })