Fixed bug RF#29521: HTML math output not always XHTML compatible

The characters < and & are not allowed in a script tag in XHTML.
So since the HTML converter uses script tags for math elements,
whenever these characters appear in a value the value is wrapped
in a CDATA section to make the output XHTML compatible.

Author: gettalong

lib/kramdown/converter/html.rb

@@ -315,7 +315,8 @@ def convert_smart_quote(el, indent)
 
       def convert_math(el, indent)
         block = (el.options[:category] == :block)
-        "<script type=\"math/tex#{block ? '; mode=display' : ''}\">#{el.value}</script>#{block ? "\n" : ''}"
+        value = (el.value =~ /<|&/ ? "<![CDATA[#{el.value}]]>" : el.value)
+        "<script type=\"math/tex#{block ? '; mode=display' : ''}\">#{value}</script>#{block ? "\n" : ''}"
       end
 
       def convert_abbreviation(el, indent)

lib/kramdown/parser/html.rb

@@ -529,7 +529,7 @@ def is_math_tag?(el)
 
         def handle_math_tag(el)
           set_basics(el, :math, :category => (el.attr['type'] =~ /mode=display/ ? :block : :span))
-          el.value = el.children.shift.value
+          el.value = el.children.shift.value.sub(/\A<!\[CDATA\[(.*)\]\]>\z/m, '\1')
           el.attr.delete('type')
         end
 

test/testcases/block/15_math/normal.html

@@ -6,10 +6,10 @@
 <p><script type="math/tex">\lambda_\alpha > 5</script>
 This is a para.</p>
 
-<script type="math/tex; mode=display">\begin{align*}
+<script type="math/tex; mode=display"><![CDATA[\begin{align*}
 &=5 \\
 &=6 \\
-\end{align*}</script>
+\end{align*}]]></script>
 
 <script type="math/tex; mode=display">5+5</script>