Flush can not check for unclosed elements, as more data might be encoded
after Flush is called. Close implicitly calls Flush and also checks that
all opened elements are closed as well.
Fixes #53346
Change-Id: I889b9f5ae54e5dfabb9e6948d96c5ed7bc1110f9
Reviewed-on: https://go-review.googlesource.com/c/go/+/424777
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com> Reviewed-by: David Chase <drchase@google.com>