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 1d15ad0007893a40f381de7c4a10ae80d325905e..c42ac5b89a7f5bcfa7f536dc9f62b00923a55eca 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1470,10 +1470,16 @@ class JSReceiver: public HeapObject {
                                                       String* name);
   PropertyAttributes GetLocalPropertyAttribute(String* name);
 
+  inline PropertyAttributes GetElementAttribute(uint32_t index);
+  PropertyAttributes GetElementAttributeWithReceiver(JSReceiver* receiver,
+                                                     uint32_t index);
+  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();
@@ -1688,6 +1694,7 @@ class JSObject: public JSReceiver {
       LookupResult* result,
       String* name,
       bool continue_search);
+  PropertyAttributes GetLocalElementAttribute(uint32_t index);
 
   static void DefineAccessor(Handle<JSObject> object,
                              Handle<String> name,