Runtime assert added to %NormalizeElements.

BUG=399654
LOG=N
R=danno@chromium.org

Review URL: https://codereview.chromium.org/423073007

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22809 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/runtime.cc

@@ -15092,6 +15092,8 @@ RUNTIME_FUNCTION(Runtime_NormalizeElements) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, array, 0);
+  RUNTIME_ASSERT(!array->HasExternalArrayElements() &&
+                 !array->HasFixedTypedArrayElements());
   JSObject::NormalizeElements(array);
   return *array;
 }