Revert #1091 Remove unboxed object code phase 1 + extras.

This should be the last code backout for this. merging this branch
should get us back to the way we were (+ additional code changes for
later changes) as fasr as the unused unboxed code is concerned.

1 files changed, 5 insertions, 0 deletions

diff --git a/js/src/vm/ReceiverGuard.h b/js/src/vm/ReceiverGuard.h
index c14f0d83b..459cc0012 100644
--- a/js/src/vm/ReceiverGuard.h
+++ b/js/src/vm/ReceiverGuard.h
@@ -28,6 +28,11 @@ namespace js {
 // TypedObject: The structure of a typed object is determined by its group.
 //   All typed objects with the same group have the same class, prototype, and
 //   own properties.
+//
+// UnboxedPlainObject: The structure of an unboxed plain object is determined
+//   by its group and its expando object's shape, if there is one. All unboxed
+//   plain objects with the same group and expando shape have the same
+//   properties except those stored in the expando's dense elements.
 
 class HeapReceiverGuard;
 class RootedReceiverGuard;