LibWeb: Fix tokenization of attributes with empty attributes

We were neglecting to emit start tags for tags where the last attribute
had no value.

Also fix a parse error TODO that I hit while looking at this.

Libraries/LibWeb/Parser/HTMLTokenizer.cpp

@@ -895,7 +895,7 @@ _StartOfFunction:
                 }
                 ON('>')
                 {
-                    SWITCH_TO(Data);
+                    SWITCH_TO_AND_EMIT_CURRENT_TOKEN(Data);
                 }
                 ON_EOF
                 {
@@ -925,7 +925,8 @@ _StartOfFunction:
                 }
                 ON('>')
                 {
-                    TODO();
+                    PARSE_ERROR();
+                    SWITCH_TO_AND_EMIT_CURRENT_TOKEN(Data);
                 }
                 ANYTHING_ELSE
                 {