Add internal operation that converts a growable list to a fixed list.

runtime/lib/growable_array.cc

Index: runtime/lib/growable_array.cc
diff --git a/runtime/lib/growable_array.cc b/runtime/lib/growable_array.cc
index 34f60a0f1fe21aa36093b69225c565fe64c72f9f..c6ec61d284fb35f7ee8f407a92a170eaa9cf0ed9 100644
--- a/runtime/lib/growable_array.cc
+++ b/runtime/lib/growable_array.cc
@@ -91,4 +91,11 @@ DEFINE_NATIVE_ENTRY(GrowableList_setData, 2) {
   return Object::null();
 }
 
+
+DEFINE_NATIVE_ENTRY(GrowableList_toFixedLength, 1) {
+  const GrowableObjectArray& array =
+      GrowableObjectArray::CheckedHandle(arguments->NativeArgAt(0));
+  return Array::MakeArray(array);

[srdjan, 2014/02/05 16:39:59]

Maybe use GET_NON_NULL_NATIVE_ARGUMENT instead of CheckedHandle. The difference
is that the former throws an exception if argument is not GrowableObjectArray,
while the later is a little faster but crashes the VM in such case. Typically,
CheckedHandle is used only on receiver when it is known.

[Ivan Posva, 2014/02/06 16:57:00]

What Srdjan said. You are not guaranteed that the value passed here is correct
(which is only considered to be the case for receivers) and thus you need to use
the throwing variant of the handle creation.

[Lasse Reichstein Nielsen, 2014/02/10 09:01:54]

Done.

+}
+
 }  // namespace dart