Handled return-value of SetElement in some cases, or avoided it in other.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index de15a7398d7fd8c86242247e778a724153cef8a7..e9e9f635c0b26b5b1b33dce74aaf3c5258bb6c95 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1515,6 +1515,12 @@ class JSObject: public HeapObject {
   inline bool HasElement(uint32_t index);
   bool HasElementWithReceiver(JSObject* receiver, uint32_t index);
 
+  // Computes the new capacity when expanding the elements of a JSObject.
+  static int NewElementsCapacity(int old_capacity) {
+    // (old_capacity + 50%) + 16
+    return old_capacity + (old_capacity >> 1) + 16;
+  }
+
   // Tells whether the index'th element is present and how it is stored.
   enum LocalElementType {
     // There is no element with given index.