Test

Fix GH-21688: SEGV in C14N on empty HTMLDocument. #1581

Job	Run time
Generate Matrix	9s
Suite / MACOS_ARM64_DEBUG_NTS	21m 43s
Suite / ALPINE_X64_ASAN_DEBUG_ZTS	31m 53s
Suite / LINUX_X64_RELEASE_NTS	26m 21s
Suite / LINUX_X64_ASAN_DEBUG_ZTS	41m 14s
Suite / WINDOWS_X64_ZTS	27m 53s
Suite / LINUX_X32_DEBUG_ZTS	12m 49s
Suite / FREEBSD_NTS	23m 13s
Suite / BENCHMARKING	15m 59s
Suite / COMMUNITY_${{ matrix.type }}	0s
Suite / MSAN	0s
Suite / PECL	0s
Suite / LINUX_PPC64_ASAN_DEBUG_ZTS	0s
Suite / SOLARIS	0s
Suite / COVERAGE	0s
Suite / OPCACHE_VARIATION	0s
Suite / LIBMYSQLCLIENT	0s
	3h 21m 14s

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