[Object.observe] Don't force normalization of elements for observed objects

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 5646 matching lines @@
   // Bit field 3.
   inline uint32_t bit_field3();
   inline void set_bit_field3(uint32_t bits);
 
   class EnumLengthBits:             public BitField<int,   0, 11> {};
   class NumberOfOwnDescriptorsBits: public BitField<int,  11, 11> {};
   class IsShared:                   public BitField<bool, 22,  1> {};
   class FunctionWithPrototype:      public BitField<bool, 23,  1> {};
   class DictionaryMap:              public BitField<bool, 24,  1> {};
   class OwnsDescriptors:            public BitField<bool, 25,  1> {};
-  class IsObserved:                 public BitField<bool, 26,  1> {};
+  class HasInstanceCallHandler:     public BitField<bool, 26,  1> {};
   class Deprecated:                 public BitField<bool, 27,  1> {};
   class IsFrozen:                   public BitField<bool, 28,  1> {};
   class IsUnstable:                 public BitField<bool, 29,  1> {};
   class IsMigrationTarget:          public BitField<bool, 30,  1> {};
 
   // Tells whether the object in the prototype property will be used
   // for instances created from this function.  If the prototype
   // property is set to a value that is not a JSObject, the prototype
   // property will not be used to create instances of the function.
   // See ECMA-262, 13.2.2.
@@ skipping 42 matching lines @@
   // See https://bugzilla.mozilla.org/show_bug.cgi?id=248549.
   inline void set_is_undetectable() {
     set_bit_field(bit_field() | (1 << kIsUndetectable));
   }
 
   inline bool is_undetectable() {
     return ((1 << kIsUndetectable) & bit_field()) != 0;
   }
 
   // Tells whether the instance has a call-as-function handler.
-  inline void set_has_instance_call_handler() {
-    set_bit_field(bit_field() | (1 << kHasInstanceCallHandler));
+  inline void set_is_observed() {
+    set_bit_field(bit_field() | (1 << kIsObserved));
   }
 
-  inline bool has_instance_call_handler() {
-    return ((1 << kHasInstanceCallHandler) & bit_field()) != 0;
+  inline bool is_observed() {
+    return ((1 << kIsObserved) & bit_field()) != 0;
   }
 
   inline void set_is_extensible(bool value);
   inline bool is_extensible();
 
   inline void set_elements_kind(ElementsKind elements_kind) {
     ASSERT(elements_kind < kElementsKindCount);
     ASSERT(kElementsKindCount <= (1 << kElementsKindBitCount));
-    ASSERT(!is_observed() ||
-           elements_kind == DICTIONARY_ELEMENTS ||
-           elements_kind == NON_STRICT_ARGUMENTS_ELEMENTS ||
-           IsExternalArrayElementsKind(elements_kind));
     set_bit_field2((bit_field2() & ~kElementsKindMask) |
         (elements_kind << kElementsKindShift));
     ASSERT(this->elements_kind() == elements_kind);
   }
 
   inline ElementsKind elements_kind() {
     return static_cast<ElementsKind>(
         (bit_field2() & kElementsKindMask) >> kElementsKindShift);
   }
 
@@ skipping 232 matching lines @@
     if (length != kInvalidEnumCache) {
       ASSERT(length >= 0);
       ASSERT(length == 0 || instance_descriptors()->HasEnumCache());
       ASSERT(length <= NumberOfOwnDescriptors());
     }
     set_bit_field3(EnumLengthBits::update(bit_field3(), length));
   }
 
   inline bool owns_descriptors();
   inline void set_owns_descriptors(bool is_shared);
-  inline bool is_observed();
-  inline void set_is_observed(bool is_observed);
+  inline bool has_instance_call_handler();
+  inline void set_has_instance_call_handler();
   inline void freeze();
   inline bool is_frozen();
   inline void mark_unstable();
   inline bool is_stable();
   inline void set_migration_target(bool value);
   inline bool is_migration_target();
   inline void deprecate();
   inline bool is_deprecated();
   inline bool CanBeDeprecated();
   // Returns a non-deprecated version of the input. If the input was not
@@ skipping 238 matching lines @@
 
   STATIC_CHECK(kInstanceTypeOffset == Internals::kMapInstanceTypeOffset);
 
   // Bit positions for bit field.
   static const int kUnused = 0;  // To be used for marking recently used maps.
   static const int kHasNonInstancePrototype = 1;
   static const int kIsHiddenPrototype = 2;
   static const int kHasNamedInterceptor = 3;
   static const int kHasIndexedInterceptor = 4;
   static const int kIsUndetectable = 5;
-  static const int kHasInstanceCallHandler = 6;
+  static const int kIsObserved = 6;
   static const int kIsAccessCheckNeeded = 7;
 
   // Bit positions for bit field 2
   static const int kIsExtensible = 0;
   static const int kStringWrapperSafeForDefaultValueOf = 1;
   static const int kAttachedToSharedFunctionInfo = 2;
   // No bits can be used after kElementsKindFirstBit, they are all reserved for
   // storing ElementKind.
   static const int kElementsKindShift = 3;
   static const int kElementsKindBitCount = 5;
@@ skipping 4206 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_