Also use binary search to search through valid entries.

src/objects-inl.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 1897 matching lines @@
 
 void DescriptorArray::SetNumberOfDescriptors(int number_of_descriptors) {
   WRITE_FIELD(
       this, kDescriptorLengthOffset, Smi::FromInt(number_of_descriptors));
 }
 
 
 // Perform a binary search in a fixed array. Low and high are entry indices. If
 // there are three entries in this array it should be called with low=0 and
 // high=2.
-template<typename T>
-int BinarySearch(T* array, String* name, int low, int high) {
+template<SearchMode search_mode, typename T>
+int BinarySearch(T* array, String* name, int low, int high, int valid_entries) {
   uint32_t hash = name->Hash();
   int limit = high;
 
   ASSERT(low <= high);
 
   while (low != high) {
     int mid = (low + high) / 2;
     String* mid_name = array->GetSortedKey(mid);
     uint32_t mid_hash = mid_name->Hash();
 
     if (mid_hash >= hash) {
       high = mid;
     } else {
       low = mid + 1;
     }
   }
 
   for (; low <= limit; ++low) {
     int sort_index = array->GetSortedKeyIndex(low);
     String* entry = array->GetKey(sort_index);
     if (entry->Hash() != hash) break;
-    if (entry->Equals(name)) return sort_index;
+    if (entry->Equals(name)) {
+      if (search_mode == ALL_ENTRIES || sort_index < valid_entries) {
+        return sort_index;
+      }
+      return T::kNotFound;
+    }
   }
 
   return T::kNotFound;
 }
 
 // Perform a linear search in this fixed array. len is the number of entry
 // indices that are valid.
 template<SearchMode search_mode, typename T>
 int LinearSearch(T* array, String* name, int len, int valid_entries) {
   uint32_t hash = name->Hash();
@@ skipping 23 matching lines @@
     SLOW_ASSERT(array->IsSortedNoDuplicates(valid_entries));
   } else {
     SLOW_ASSERT(array->IsSortedNoDuplicates());
   }
 
   int nof = array->number_of_entries();
   if (nof == 0) return T::kNotFound;
 
   // Fast case: do linear search for small arrays.
   const int kMaxElementsForLinearSearch = 8;
-  if (search_mode == VALID_ENTRIES ||
-      (search_mode == ALL_ENTRIES && nof < kMaxElementsForLinearSearch)) {
+  if ((search_mode == ALL_ENTRIES &&
+       nof <= kMaxElementsForLinearSearch) ||
+      (search_mode == VALID_ENTRIES &&
+       valid_entries <= kMaxElementsForLinearSearch)) {
     return LinearSearch<search_mode>(array, name, nof, valid_entries);
   }
 
   // Slow case: perform binary search.
-  return BinarySearch(array, name, 0, nof - 1);
+  return BinarySearch<search_mode>(array, name, 0, nof - 1, valid_entries);
 }
 
 
 int DescriptorArray::Search(String* name, int valid_descriptors) {
   return internal::Search<VALID_ENTRIES>(this, name, valid_descriptors);
 }
 
 
 int DescriptorArray::SearchWithCache(String* name, Map* map) {
   int number_of_own_descriptors = map->NumberOfOwnDescriptors();
@@ skipping 3555 matching lines @@
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_