fixup! Make the serializer behave like a normal func with unknown kwargs

Author: gsnedders

html5lib/tests/test_serializer.py

@@ -149,6 +149,11 @@ def testComment():
     throwsWithLatin1([["Comment", "\u0101"]])
 
 
+def testThrowsUnknownOption():
+    with pytest.raises(TypeError):
+        HTMLSerializer(foobar=None)
+
+
 @pytest.mark.parametrize("c", list("\t\n\u000C\x20\r\"'=<>`"))
 def testSpecQuoteAttribute(c):
     input_ = [["StartTag", "http://www.w3.org/1999/xhtml", "span",