pkg/third_party/html5lib: lots of cleanup

pkg/third_party/html5lib/lib/src/utils.dart

Index: pkg/third_party/html5lib/lib/src/utils.dart
diff --git a/pkg/third_party/html5lib/lib/src/utils.dart b/pkg/third_party/html5lib/lib/src/utils.dart
index ca81a414c8178ffd0ec6d212593b10007663b6eb..c4961d19c5d43198fe26ec5149adcb704af9ce41 100644
--- a/pkg/third_party/html5lib/lib/src/utils.dart
+++ b/pkg/third_party/html5lib/lib/src/utils.dart
@@ -1,7 +1,6 @@
 /** Misc things that were useful when porting the code from Python. */
 library utils;
 
-import 'dart:collection';
 import 'constants.dart';
 
 typedef bool Predicate();
@@ -75,7 +74,7 @@ String padWithZeros(String str, int size) {
 /**
  * Format a string like Python's % string format operator. Right now this only
  * supports a [data] dictionary used with %s or %08x. Those were the only things
- * needed for [errorMessages].
+ * needed for [ERROR_MESSAGES].
  */
 String formatStr(String format, Map data) {
   if (data == null) return format;