Implement tracking and optimizations of packed arrays

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 0bc93c2ff252635e7d5fe4dafcb2b8b06f63eb7d..2d14a93e845f17c86f15678584def301aa76e615 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -5040,7 +5040,7 @@ Local<Object> Array::CloneElementAt(uint32_t index) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Array::CloneElementAt()", return Local<Object>());
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  if (!self->HasFastElements()) {
+  if (!self->HasFastObjectElements()) {
     return Local<Object>();
   }
   i::FixedArray* elms = i::FixedArray::cast(self->elements());