Reland: track global accesses to constant types

src/objects.h

 // Copyright 2012 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 9811 matching lines @@
 
 
 class PropertyCell : public HeapObject {
  public:
   // [value]: value of the global property.
   DECL_ACCESSORS(value, Object)
   // [dependent_code]: dependent code that depends on the type of the global
   // property.
   DECL_ACCESSORS(dependent_code, DependentCode)
 
+  PropertyCellConstantType GetConstantType();
+
   // Computes the new type of the cell's contents for the given value, but
   // without actually modifying the details.
   static PropertyCellType UpdatedType(Handle<PropertyCell> cell,
                                       Handle<Object> value,
                                       PropertyDetails details);
   static Handle<Object> UpdateCell(Handle<NameDictionary> dictionary, int entry,
                                    Handle<Object> value,
                                    PropertyDetails details);
 
   static Handle<PropertyCell> InvalidateEntry(Handle<NameDictionary> dictionary,
@@ skipping 1251 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_