test: extend noescape bytes.Buffer test suite
test: extend noescape bytes.Buffer test suite

Added some more cases that should be guarded against regression.

Change-Id: I9f1dda2fd0be9b6e167ef1cc018fc8cce55c066c
Reviewed-on: https://go-review.googlesource.com/134017
Run-TryBot: Iskander Sharipov <a698043bc2fd5ebc21d5b6bbc66ee53917362fef@intel.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

cloudflare/go,cloudflare/go,akutz/go,josharian/go,CAFxX/go,golang/go,akutz/go,CAFxX/go,nawawi/go,akutz/go,cloudflare/go,akutz/go,CAFxX/go,golang/go,akutz/go,josharian/go,golang/go,nawawi/go,josharian/go,nawawi/go,nawawi/go,cloudflare/go,nawawi/go,cloudflare/go,nawawi/go,CAFxX/go,golang/go,akutz/go,golang/go,josharian/go,josharian/go,golang/go,cloudflare/go,josharian/go,josharian/go,cloudflare/go,CAFxX/go,golang/go,josharian/go,akutz/go,nawawi/go,CAFxX/go,akutz/go,cloudflare/go,CAFxX/go,CAFxX/go,nawawi/go,golang/go