Revert revision 37912 - it seems to be causing errors and flake on the pub builders

pkg/barback/lib/src/utils.dart

Index: pkg/barback/lib/src/utils.dart
===================================================================
--- pkg/barback/lib/src/utils.dart	(revision 37928)
+++ pkg/barback/lib/src/utils.dart	(working copy)
@@ -336,12 +336,3 @@
 /// [toString], so we remove that if it exists.
 String getErrorMessage(error) =>
   error.toString().replaceFirst(_exceptionPrefix, '');
-
-/// Returns a human-friendly representation of [duration].
-String niceDuration(Duration duration) {
-  var result = duration.inMinutes > 0 ? "${duration.inMinutes}:" : "";
-
-  var s = duration.inSeconds % 59;
-  var ms = (duration.inMilliseconds % 1000) ~/ 100;
-  return result + "$s.${ms}s";
-}