[runtime] Replace hidden_string with a 0-hash-code private symbol

src/objects.h

 // Copyright 2015 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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 2175 matching lines @@
       Handle<AccessorInfo> info);
 
   // The result must be checked first for exceptions. If there's no exception,
   // the output parameter |done| indicates whether the interceptor has a result
   // or not.
   MUST_USE_RESULT static MaybeHandle<Object> GetPropertyWithInterceptor(
       LookupIterator* it, bool* done);
 
   // Accessors for hidden properties object.
   //
-  // Hidden properties are not own properties of the object itself.
-  // Instead they are stored in an auxiliary structure kept as an own
-  // property with a special name Heap::hidden_string(). But if the
-  // receiver is a JSGlobalProxy then the auxiliary object is a property
-  // of its prototype, and if it's a detached proxy, then you can't have
-  // hidden properties.
+  // Hidden properties are not own properties of the object itself.  Instead
+  // they are stored in an auxiliary structure kept as an own property with a
+  // special name Heap::hidden_properties_symbol(). But if the receiver is a
+  // JSGlobalProxy then the auxiliary object is a property of its prototype, and
+  // if it's a detached proxy, then you can't have hidden properties.
 
   // Sets a hidden property on this object. Returns this object if successful,
   // undefined if called on a detached proxy.
   static Handle<Object> SetHiddenProperty(Handle<JSObject> object,
                                           Handle<Name> key,
                                           Handle<Object> value);
   // Gets the value of a hidden property with the given key. Returns the hole
   // if the property doesn't exist (or if called on a detached proxy),
   // otherwise returns the value set for the key.
   Object* GetHiddenProperty(Handle<Name> key);
@@ skipping 6759 matching lines @@
   static const int kMaxArrayIndexSize = 10;
   STATIC_ASSERT(kMaxArrayIndexSize < (1 << kArrayIndexLengthBits));
 
   // Max char codes.
   static const int32_t kMaxOneByteCharCode = unibrow::Latin1::kMaxChar;
   static const uint32_t kMaxOneByteCharCodeU = unibrow::Latin1::kMaxChar;
   static const int kMaxUtf16CodeUnit = 0xffff;
   static const uint32_t kMaxUtf16CodeUnitU = kMaxUtf16CodeUnit;
   static const uc32 kMaxCodePoint = 0x10ffff;
 
-  // Value of hash field containing computed hash equal to zero.
-  static const int kEmptyStringHash = kIsNotArrayIndexMask;
-
   // Maximal string length.
   static const int kMaxLength = (1 << 28) - 16;
 
   // Max length for computing hash. For strings longer than this limit the
   // string length is used as the hash value.
   static const int kMaxHashCalcLength = 16383;
 
   // Limit for truncation in short printing.
   static const int kMaxShortPrintLength = 1024;
 
@@ skipping 1854 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_