Even though calling delete on a super property will ultimately throw a
ReferenceError, we must return the allocated register for the result of
the delete operation (which would normally be a boolean). If the delete
operation is used in a return statement, the bytecode generator for the
return statement must be able to assume the statement had some output.
(cherry picked from commit 5947c37637f8ea3d4c323a04e5e5dfe9fad5a4d7)
Timothy Flynn
e0a25b5cdd