More cleanup related to setting array.length

src/elements.h

Index: src/elements.h
diff --git a/src/elements.h b/src/elements.h
index 66a96e8f3ddd35c2b5a222cc05545b738057bd16..18e47d2146d6ccdc3525ff5627bd9b42450f2c03 100644
--- a/src/elements.h
+++ b/src/elements.h
@@ -74,9 +74,7 @@ class ElementsAccessor {
   // changing array sizes as defined in EcmaScript 5.1 15.4.5.2, i.e. array that
   // have non-deletable elements can only be shrunk to the size of highest
   // element that is non-deletable.
-  MUST_USE_RESULT virtual MaybeHandle<Object> SetLength(
-      Handle<JSArray> holder,
-      Handle<Object> new_length) = 0;
+  virtual void SetLength(Handle<JSArray> holder, uint32_t new_length) = 0;
 
   // Modifies both the length and capacity of a JSArray, resizing the underlying
   // backing store as necessary. This method does NOT honor the semantics of