Adds the same interceptors from dart2js as JsPeerInterfaces
and handles typeof differences in getReifiedType. These must
be JsPeerInterfaces so that Object members can be stored in
their prototype. Tests are added so that dart2js and ddc are
consistent.
Change-Id: Iadc3dd26957c0a21b4039c49c1c1ff162ae286e6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/321748
Reviewed-by: Stephen Adams <sra@google.com>