Fix treewalkers to never generate DOCTYPE tokens with None as the name (replaced with an empty unicode string)
Fix treewalkers to never generate DOCTYPE tokens with None as the name (replaced with an empty unicode string)

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extra : convert_revision : svn%3Aacbfec75-9323-0410-a652-858a13e371e0/trunk%40882

mindw/html5lib-python,html5lib/html5lib-python,html5lib/html5lib-python,html5lib/html5lib-python,alex/html5lib-python,mgilson/html5lib-python,mgilson/html5lib-python,ordbogen/html5lib-python,dstufft/html5lib-python,alex/html5lib-python,alex/html5lib-python,ordbogen/html5lib-python,dstufft/html5lib-python,mindw/html5lib-python,gsnedders/html5lib-python,dstufft/html5lib-python,mindw/html5lib-python,gsnedders/html5lib-python,mgilson/html5lib-python,ordbogen/html5lib-python