[stubs] Properly handle read-only properties in StoreGlobalViaContextStub.

src/property-details.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_PROPERTY_DETAILS_H_
 #define V8_PROPERTY_DETAILS_H_
 
 #include "include/v8.h"
 #include "src/allocation.h"
 #include "src/utils.h"
@@ skipping 302 matching lines @@
   bool IsDontEnum() const { return (attributes() & DONT_ENUM) != 0; }
   PropertyCellType cell_type() const {
     return PropertyCellTypeField::decode(value_);
   }
 
   // Bit fields in value_ (type, shift, size). Must be public so the
   // constants can be embedded in generated code.
   class KindField : public BitField<PropertyKind, 0, 1> {};
   class LocationField : public BitField<PropertyLocation, 1, 1> {};
   class AttributesField : public BitField<PropertyAttributes, 2, 3> {};
+  static const int kAttributesReadOnlyMask =
+      (READ_ONLY << AttributesField::kShift);
 
   // Bit fields for normalized objects.
   class PropertyCellTypeField : public BitField<PropertyCellType, 5, 2> {};
   class DictionaryStorageField : public BitField<uint32_t, 7, 24> {};
 
   // Bit fields for fast objects.
   class RepresentationField : public BitField<uint32_t, 5, 4> {};
   class DescriptorPointer
       : public BitField<uint32_t, 9, kDescriptorIndexBitCount> {};  // NOLINT
   class FieldIndexField
@@ skipping 32 matching lines @@
   uint32_t value_;
 };
 
 
 std::ostream& operator<<(std::ostream& os,
                          const PropertyAttributes& attributes);
 std::ostream& operator<<(std::ostream& os, const PropertyDetails& details);
 } }  // namespace v8::internal
 
 #endif  // V8_PROPERTY_DETAILS_H_