Object.observe: generate change records for indexed properties.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 87ae24ab640f02d1e73e9291a81743a241ac5eec..1b332b219ee9792648688e2f7c36a099f78d02b8 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1470,10 +1470,18 @@ class JSReceiver: public HeapObject {
                                                       String* name);
   PropertyAttributes GetLocalPropertyAttribute(String* name);
 
+  inline PropertyAttributes GetElementAttribute(uint32_t index);
+  inline PropertyAttributes GetElementAttributeWithReceiver(
+      JSReceiver* receiver,
+      uint32_t index,
+      bool continue_search);
+  inline PropertyAttributes GetLocalElementAttribute(uint32_t index);
+
   // Can cause a GC.
   inline bool HasProperty(String* name);
   inline bool HasLocalProperty(String* name);
   inline bool HasElement(uint32_t index);
+  inline bool HasLocalElement(uint32_t index);
 
   // Return the object's prototype (might be Heap::null_value()).
   inline Object* GetPrototype();
@@ -1498,10 +1506,10 @@ class JSReceiver: public HeapObject {
   Smi* GenerateIdentityHash();
 
  private:
-  PropertyAttributes GetPropertyAttribute(JSReceiver* receiver,
-                                          LookupResult* result,
-                                          String* name,
-                                          bool continue_search);
+  PropertyAttributes GetPropertyAttributeForResult(JSReceiver* receiver,
+                                                   LookupResult* result,
+                                                   String* name,
+                                                   bool continue_search);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSReceiver);
 };
@@ -1688,6 +1696,9 @@ class JSObject: public JSReceiver {
       LookupResult* result,
       String* name,
       bool continue_search);
+  PropertyAttributes GetElementAttributeWithReceiver(JSReceiver* receiver,
+                                                     uint32_t index,
+                                                     bool continue_search);
 
   static void DefineAccessor(Handle<JSObject> object,
                              Handle<String> name,
@@ -2196,6 +2207,14 @@ class JSObject: public JSReceiver {
                                                       Object* structure,
                                                       uint32_t index,
                                                       Object* holder);
+  MUST_USE_RESULT PropertyAttributes GetElementAttributeWithInterceptor(
+      JSReceiver* receiver,
+      uint32_t index,
+      bool continue_search);
+  MUST_USE_RESULT PropertyAttributes GetElementAttributeWithoutInterceptor(
+      JSReceiver* receiver,
+      uint32_t index,
+      bool continue_search);
   MUST_USE_RESULT MaybeObject* SetElementWithCallback(
       Object* structure,
       uint32_t index,