Introduce basic type feedback for for-in statements to avoid deopts.

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4045 matching lines @@
 
   // The object that indicates a megamorphic state.
   static inline Handle<Object> MegamorphicSentinel(Isolate* isolate);
 
   // A raw version of the uninitialized sentinel that's safe to read during
   // garbage collection (e.g., for patching the cache).
   static inline Object* RawUninitializedSentinel(Heap* heap);
 
   // Casting.
   static inline TypeFeedbackCells* cast(Object* obj);
+
+  static const int kForInFastCaseMarker = 0;
+  static const int kForInSlowCaseMarker = 1;
 };
 
 
 // Forward declaration.
 class SafepointEntry;
 class TypeFeedbackInfo;
 
 // Code describes objects with on-the-fly generated machine code.
 class Code: public HeapObject {
  public:
@@ skipping 4347 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_