fixup! Fix #11, #12: quote attributes that need escaping in legacy browsers

Author: gsnedders

html5lib/tests/serializer-testdata/core.test

@@ -242,7 +242,7 @@
         },
         {
             "expected": [
-                "<span title=foo\u000bbar>"
+                "<span title=\"foo\u000bbar\">"
             ],
             "input": [
                 [