Fix setting array length to be ES5 conform.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 3187467b380a9cde1d4355ea007238fb1075e317..a4f95aa033bd2f92b0f8899efda106bb3d245d12 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1735,7 +1735,6 @@ class JSObject: public JSReceiver {
   MUST_USE_RESULT MaybeObject* SetFastDoubleElementsCapacityAndLength(
       int capacity,
       int length);
-  MUST_USE_RESULT MaybeObject* SetSlowElements(Object* length);
 
   // Lookup interceptors are used for handling properties controlled by host
   // objects.
@@ -2987,9 +2986,6 @@ class NumberDictionary: public Dictionary<NumberDictionaryShape, uint32_t> {
   // requires_slow_elements returns false.
   inline uint32_t max_number_key();
 
-  // Remove all entries were key is a number and (from <= key && key < to).
-  void RemoveNumberEntries(uint32_t from, uint32_t to);
-
   // Bit masks.
   static const int kRequiresSlowElementsMask = 1;
   static const int kRequiresSlowElementsTagSize = 1;