[WIP] JSForInLowering and JSForInHasOwnProperty.

src/compiler/types.h

 // Copyright 2014 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.
 
 #ifndef V8_COMPILER_TYPES_H_
 #define V8_COMPILER_TYPES_H_
 
 #include "src/base/compiler-specific.h"
 #include "src/conversions.h"
 #include "src/globals.h"
@@ skipping 161 matching lines @@
   V(DetectableObject,             kFunction | kBoundFunction | \
                                   kOtherCallable | kOtherObject) \
   V(DetectableReceiver,           kDetectableObject | kProxy) \
   V(DetectableReceiverOrNull,     kDetectableReceiver | kNull) \
   V(Object,                       kDetectableObject | kOtherUndetectable) \
   V(Receiver,                     kObject | kProxy) \
   V(ReceiverOrUndefined,          kReceiver | kUndefined) \
   V(ReceiverOrNullOrUndefined,    kReceiver | kNull | kUndefined) \
   V(SymbolOrReceiver,             kSymbol | kReceiver) \
   V(StringOrReceiver,             kString | kReceiver) \
+  V(StringOrUndefined,            kString | kUndefined) \
   V(Unique,                       kBoolean | kUniqueName | kNull | \
                                   kUndefined | kReceiver) \
   V(Internal,                     kHole | kExternalPointer | kOtherInternal) \
   V(NonInternal,                  kPrimitive | kReceiver) \
   V(NonNumber,                    kUnique | kString | kInternal) \
   V(Any,                          0xfffffffeu)
 
 // clang-format on
 
 /*
@@ skipping 470 matching lines @@
                           RangeType::Limits* limits, Zone* zone);
   static Type* NormalizeUnion(Type* unioned, int size, Zone* zone);
   static Type* NormalizeRangeAndBitset(Type* range, bitset* bits, Zone* zone);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_TYPES_H_