pkg/third_party/html5lib: lots of cleanup

pkg/third_party/html5lib/test/parser_test.dart

 library parser_test;
 
 import 'dart:convert';
 import 'dart:io';
 import 'package:path/path.dart' as pathos;
 import 'package:unittest/unittest.dart';
 import 'package:html5lib/dom.dart';
 import 'package:html5lib/parser.dart';
 import 'package:html5lib/parser_console.dart' as parser_console;
-import 'package:html5lib/src/constants.dart';
 import 'package:html5lib/src/inputstream.dart' as inputstream;
-import 'package:html5lib/src/tokenizer.dart';
-import 'package:html5lib/src/utils.dart';
 import 'support.dart';
 
 // Run the parse error checks
 // TODO(jmesserly): presumably we want this on by default?
 final checkParseErrors = false;
 
 String namespaceHtml(String expected) {
   // TODO(jmesserly): this is a workaround for http://dartbug.com/2979
   // We can't do regex replace directly =\
   // final namespaceExpected = new RegExp(@"^(\s*)<(\S+)>", multiLine: true);
@@ skipping 91 matching lines @@
 /** Extract the name for the test based on the test input data. */
 _nameFor(String input) {
   // Using JSON.decode to unescape other unicode characters
   var escapeQuote = input
       .replaceAll(new RegExp('\\\\.'), '_')
       .replaceAll(new RegExp('\u0000'), '_')
       .replaceAll('"', '\\"')
       .replaceAll(new RegExp('[\n\r\t]'),'_');
   return JSON.decode('"$escapeQuote"');
 }