test(report): test serialization of xmlns=""

[AirQuick]

Just adds some tests for verifying this code:

xspec/src/reporter/format-utils.xsl

Lines 100 to 108 in b3a31af

	<!-- Output xmlns="" to undeclare the default namespace -->
	<xsl:if
	test="
	($level ge 1)
	and exists($parent-namespaces[name() = ''])
	and empty($namespaces[name() = ''])">
	<xsl:text> </xsl:text>
	<span class="xmlns">xmlns=""</span>
	</xsl:if>