If we are trimming the whole array, just return the empty fixed array.

Review URL: https://chromiumcodereview.appspot.com/10911054

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12427 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/handles.cc

@@ -799,7 +799,7 @@ Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object,
     Handle<FixedArray> storage =
         isolate->factory()->NewFixedArray(next_enumeration);
 
-    dictionary->CopyEnumKeysTo(*storage);
+    storage = Handle<FixedArray>(dictionary->CopyEnumKeysTo(*storage));
     ASSERT(storage->length() == object->NumberOfLocalProperties(DONT_ENUM));
     return storage;
   }

src/objects.cc

@@ -12474,7 +12474,7 @@ void Dictionary<Shape, Key>::CopyKeysTo(
 }
 
 
-void StringDictionary::CopyEnumKeysTo(FixedArray* storage) {
+FixedArray* StringDictionary::CopyEnumKeysTo(FixedArray* storage) {
   int length = storage->length();
   ASSERT(length >= NumberOfEnumElements());
   Heap* heap = GetHeap();
@@ -12501,6 +12501,7 @@ void StringDictionary::CopyEnumKeysTo(FixedArray* storage) {
   // together by shifting them to the left (maintaining the enumeration order),
   // and trimming of the right side of the array.
   if (properties < length) {
+    if (properties == 0) return heap->empty_fixed_array();
     properties = 0;
     for (int i = 0; i < length; ++i) {
       Object* value = storage->get(i);
@@ -12511,6 +12512,7 @@ void StringDictionary::CopyEnumKeysTo(FixedArray* storage) {
     }
     RightTrimFixedArray<FROM_MUTATOR>(heap, storage, length - properties);
   }
+  return storage;
 }
 
 

src/objects.h

@@ -3128,7 +3128,7 @@ class StringDictionary: public Dictionary<StringDictionaryShape, String*> {
   }
 
   // Copies enumerable keys to preallocated fixed array.
-  void CopyEnumKeysTo(FixedArray* storage);
+  FixedArray* CopyEnumKeysTo(FixedArray* storage);
   static void DoGenerateNewEnumerationIndices(
       Handle<StringDictionary> dictionary);