fragment serialization is inconsistent

[flavorjones]

frag = Nokogiri::HTML.fragment("<p>foo</p>")
frag.to_xml     # => "<p>foo</p>\n"
frag.serialize  # => "<p>foo</p>\n"

but

frag.to_s       # => "<><p>foo</p></>"
frag.to_html    # => "<><p>foo</p></>"

[flavorjones]

aaron suggests aliasing to_s and to_html to inner_html for DocumentFragments. I concur.

[flavorjones]

HTML fragments now serialize consistently. closed by 57c2ba2.